How do you clip GIFs onto masks?
[PT: How do you clip GIFs onto masks? /END PT]
Right click on your mask layer, click Select Pixels.
Click the Folder icon and then the Raster Mask icon on the bottom right. This should create a new folder.
Duplicate your gif into your project, either by clicking and dragging it into it or by right clicking and duplicating it into your project.
Simply put your gif into the folder that you made earlier and adjust it as needed. (make sure you have the WHOLE GIF FOLDER selected and have AUTO-SELECT OFF! otherwise it'll only edit one frame)
Export it as a gif and you're done.
You CAN do this with images that have faded borders, but it is important to note that gifs will make masks with any fading solid if you export it as a gif. Exporting it as a webp will keep the fading, though.