Thanks for the crash report. It crashes because the size of your animation is too large. Spine computes the smallest rectangle that will contain all images over the entire animation. This is the size of the exported video.
To reproduce the issue I tried to export a 20k x 18k frame, which is about 1.4gb. For whatever reason the OS doesn't allow this allocation, even though I have 12gb free. The crash happens because of a bug in libgdx, which I just fixed. Now Spine can check for the failure and alert you that the size is too large. Unfortunately there's nothing I can do if the OS doesn't allow the memory to be allocated.
However, because OpenGL is used to render each exported frame, exports are limited by your GPU's max texture size, even if the OS allows the allocation mentioned above. I will add checks for that as well. This can be worked around by rendering only a portion of the animation via OpenGL and reassembling each frame. I don't know this is worth the trouble though, as a modern GPU can probably handle a 4096x4096 texture, with is 16M pixels. HD resolution of 1920x1080 is only 2M pixels, so it is unlikely for the GPU to be the limiting factor for videos of a reasonable size.
https://trello.com/card/alert-user-when ... c0059d9/61