Hi, I've done both yoga classes and yoga at home with a video. I find at home is much better. You're comfortable, you can follow at your own pace (rewind if you can't quite figure out a move).
I found the classes were good, but very distracting. It's hard to concentrate on your breathing when the guy next to you sounds like a vaccuum cleaner. Also a lot of times, the yoga teachers would come over and try to force me further into the position and it hurt. I'm really not flexible, so I wanted to go at my own pace.
Maybe try both and see what you like? Have fun! Kat