GoEasy and Julia - I've been doing mainly videos that I was doing beforehand, but just missing out the ab moves, and taking it much easier than I would have done beforehand.
Like for example, before doing the thirty day shred I would have pushed myself to keep going when I was getting tired, done all the exercises I could on the harder level, and used lighter weights on moves I found tough.
Now it's the easier version of most things (unless it's a piss easy move), using lighter weights overall, and using no weights at all on the more difficult moves. Basically getting a bit out of breath is okay, but lying in a puddle of your own sweat is bad. If you're tired, you can just sit out the rest of that move, or rest during the next move or whatever.
Other things I like are any of the Fitness Blender Low Impact cardio workouts, the Ministry of Sound Pump it Up the Ultimate dance workout (either skipping out the pump it up section, or just taking it much slower), and JessicaSmithtv who has some prenatal workouts.
Denise Austin does a few pregnancy workouts as well, but I find myself just wanting to punch her in the face.
Basically just search "pregnancy workout" or "pre natal workouts" on youtube and pick whatever takes your fancy.