I’m asking because I saw a few posts in my home feed that I can’t verify. By the way, Lemmy can’t be compared to Reddit if it doesn’t have the ability to post videos or GIFs. Think about it: what good is a social media platform without the ability to share the most popular forms of multimedia?
It’s up to the client on how to render them. Most videos I encounter in Lemmy are linked from outside sources or are on YouTube.
Edit: In addition to what clients support, it’s also up to each instance admin to define what media they allow to be uploaded. Among the possible configuration options are:
Like others have said, hosting videos is expensive both in areas of storage and bandwidth. Most Lemmy instances are run by volunteers at their cost or operate solely on donations. Admins typically ask users to host those off-server (Imgur, YouTube, Catbox, etc) and restrict what can be uploaded directly to reasonable limits.