Some of them turn into gifs on the hosting platform but you have to search google and create an account. Imgur makes you give a phone number so I didn’t make an account with them. I found pxlmo.com which only requires a name, email to make one that you can just make up and use a dedicated email if you wanna stay private. Pxlmo has a 20mb file size limit for videos. You can Google a site that lets you upload a video and compress it if it is too long. Then you just copy the link and add it to the description of your post. It will open in the in-app player on some of the Lemmy supported apps. I use Boost for Lemmy but usually you can’t embed them. Lemmy on a browser will probably open a new tab. The reason I use image/video hosting is to remain anonymous because my real name is on my YouTube.