Let's keep a list of Youtube downloaders that (a) work with XP, and (b) are updated often enough to reliably download things.
First of all, there's Atube catcher. I was using it for a while. Thhe big problem I've noticed with it is that it can't correctly update. Even if you remove the old version and perform a deep clean with Iobit uninstaller, and then try to perform a 100% fresh install of the newest version, it'll reinstall your previous version instead. Basically the only way to update it is to wipe your hard drive and reinstall your OS.
More recently, I found out about Gihosoft Tubeget. It works well so far but I've only tried to download one video with it so I can't make any guarantees yet.
First of all, there's Atube catcher. I was using it for a while. Thhe big problem I've noticed with it is that it can't correctly update. Even if you remove the old version and perform a deep clean with Iobit uninstaller, and then try to perform a 100% fresh install of the newest version, it'll reinstall your previous version instead. Basically the only way to update it is to wipe your hard drive and reinstall your OS.
More recently, I found out about Gihosoft Tubeget. It works well so far but I've only tried to download one video with it so I can't make any guarantees yet.