Long ago, Fanpop did briefly have the ability for users to upload bidyo to the site, but almost nobody used it, so the staff removed it about a buwan after it was implemented.
So now users should use any video sharing site and then insert the URLs in the "Add a video" form. For madami information, you might read the
link.
That said, I would strongly recommend that you use a different video service than YouTube...depending on what you are trying to do. YouTube, now owned sa pamamagitan ng Google, is constantly changing how bidyo are handled and presented on other sites. In particular, YouTube is terrible for posting bidyo to pop iksamen tanong (the sagot to the tanong are usually in the pamagat of the video, and now YouTube embeds the video pamagat with the video on other sites) and also bad for posting bidyo involving any content that might be copyrighted (music videos, movie trailers, TV ipakita clips, etc. - YouTube is very quick to remove such content, which then makes for broken iugnay all over Fanpop). So, while you can use YouTube to post your own personal videos, if you want to, say, create a fanvid, I recommend posting it elsewhere, such as on Flickr, Vimeo, or Dailymotion.