That thumbnail is very misleading as Spine isn't used at all - in fact the dude in the video asks for donations so he can buy a licence at the end which means he doesn't own it himself either.
The video basically shows you how to edit DragonBones json files so that they load into GMS without the need to use Spine at all.
GMS uses the official "Spine Runtimes" to render those json files into animations, and it's irrelevant where or how the json files were made, the licence requirement is quite specific in that you need a licence if you use the "official" runtimes to render them, so the video is actually showing you how to break the EULA.
It's akin to a tutorial video showing how to get around having to buy a GMS2 licence to use it and make and export games, and then having that video in the tutorials section on the forum for everyone to take advantage of.
How long before YYG go out of business and we're all up **** street?
Same thing for Spine.
As I said above, it's not the "format" that is the issue - they are just .json files.
The issue is that GMS uses the official runtimes to render them in-engine and this is why a licence is required.
If someone wrote an extension that rendered the json files within GMS
without using any of the code from the official runtimes then you could use that without needing a Spine licence. This is what Defold did - wrote their own runtimes.
I own Spine and have used DragonBones, and honestly I can say that Spine is better in every way.
Yes it costs, but as with anything you get what you pay for - much better UI, more features, quick, extensive runtime support and upkeep (they update them for many engines and languages - one of which could have been GMS but YYG shot it down when Esoteric offered to help implement an "official" runtime), and the support is top quality with replies usually within a few hours.
My personal experience with DragonBones has been pretty poor - lots of info / documentation was only in Chinese to start with or broken hard to understand English, having to sign up to dodgy looking accounts to login to it, and weeks to return an email from their support.
Turns out the DB team is only 2-3 guys doing it in their spare time and updates / fixes will come "as and when with no schedule" (their words in the reply email not mine).
There is nothing to stop you using DragonBones to render out .png images and use those within GMS, although you lose the flexibility of skeletal animation that way of course, but unless you are working on a game which you are looking to be published then tghe Essentials version would be fine - and the cost is deducted if you upgrade to Pro.
I don't understand the "I want everything for nothing" attitude that some people have in regards to the cost of things which you want to use to make your game, and presumably make money off.
To quote OP: "The basic edition is too limited for semi-serious animation".
Well if you are "semi-serious" then I don't see why having a "semi-serious" attitude and saving the money to purchase some "semi-serious" tools would be a problem?
If you want a new car do you go to a dealership and moan to the manager that all the cheaper cars aren't good enough because you want the top of the line model but can't afford it? No, you either get what you can afford and save towards the one you want, or don't get anything and continue to save until you can.
That's life.
It may seem like I'm a Spine fanboy here (and I am, it's an awesome tool) but I should also say that the GMS support of the runtimes is
very poor.
Apart from the fact that there are basic features of the runtimes not wrapped for use as JeffJ says, you won't be able to (reliably) use a version past v3.4.02 which means all those
shiny new features you see on the Spine website (Clipping, Weight Painting, Tint Black etc) you won't be able to use anyway.
Not to mention all the improvements and bugfixes to Spine itself (UI, layout etc) - we don't get those either.
I'm not 100% sure I'd even recommend anyone buy the Pro version just for using with GMS.
I've had the advantage of using Spine in other engines outside of GMS, so I'm a little more appreciative of what it can do than someone who has only experienced it's very limited support within GMS and the handful of functions it offers to interact with skeletons.
Also I agree with
@JeffJ with the fact that if YYG can't / won't keep Spine upto date and that is what's used as a big feature of GMS on the website etc, then I don't see them being able to double the workload and also implement DragonBones support to an acceptable level either on top of that.
From what's been said by YYG staff on the forums previously they are actually looking to decouple Spine from GMS and make it into an extension, which means they won't support it and it will probably become a community effort of some sort, so I wouldn't really expect an updates to what it currently is either, meaning an "official" DragnBones integration is very very unlikely too.
Maybe Esoteric could then do an official extension, but that depends on how many people actually use Spine and GMS together, and from all the posts I see on here moaning about it's price and talking to other people it seems there are probably less than 10 of us.
Maybe more that don't use forums / reddit etc, but almost certainly not a number big enough to bother putting in the work to make / upkeep an "official" runtime - if YYG don't think it's high enough priority to bother with when it's their engine that is using Spine as a feature to sell it, then the numbers can't be big enough to make it worthwhile for them.
I haven't checked recently either, but does DragonBones have runtimes for all targets that GMS supports?
Last time I checked there were only 3 I think.
Maybe you could contact one of the GMS extension writers with a view to writing an extension for you to support DB, but that would of course cost you as well, so whichever way you look at it there is going to be some cost somewhere along the way.
Apologies for the wall of text, I get carried away as I'm quite passionate in the belief that fully-featured "proper" support for Spine would make it much more attractive as an engine for a wider range of people and benefit everyone in the long term, as opposed to the half-assed "you can render a skeleton, what more do you need?" implementation we have now which isn't appealing to anyone.
At least I formatted the post, so there's that!