I used to. There's still quite a few on an old Ipod touch, but I take up so much room on my iPhone with podcasts/music that it would eat up all my HD. ;___;
I do eventually want at least my top playlist on there though. I just hate converting them into smaller/crappier formats.
Same here, I used to, but the sole purpose was to be able to show my AMVs to people who didn't know what AMVs were, not really to watch them myself. In fact, the only AMV I had on there that wasn't my own was Emong's Gothic Poetry. I watched it kind of a lot, so I wanted to have it with me when the urge struck. Every other video could wait until I got home.
I used to keep them on my ipod to show to other people and watch when I was bored. They were always my favorite videos, never my own. I've only got like 9 on there right now since I haven't updated my ipod and music in forever. Besides, nowadays if I want to watch an AMV on the go, I just use the Org App