You cannot copy and paste the video / animationanimation, then it becomes just a screenshot of the time when you copied it. GIF and APNG work if you instead go to the menu:
- Google Docs: Insert --> Image --> "Upload from your computer"
Other Google Editors
- Google Sheets: Insert --> "Insert image over cells" (does not work with "Insert image in cell")
- For Google Slides and Google Forms, I did not test it, but it should work as well with the menu.
Side remark: APNG is the smaller size version of GIF, which should be first choice for online sheets, see APNG vs GIF. Which is Better? [closed] - Stack Overflow