Where can I find videos for rosario vampire season 1?

Either youtube, or google: bittorrent rosario vampire.

Well if registered on bleachexile you can download them :)

animefreak and veoh have good quality vids

sky7anime.net or voober.com.there are some episodes on youtube but incomplete so i suggest to you those 2 websites.both 2 websites have complete episodes of the series.

Funimation (free if not expired)
Netflix (paid)
YouTube (free)
Crunchy Roll (paid)
Or if you look it up on Google there should be some English dubs available for free