No problem. I don't do too much with video to tell you the truth. Both my GF-1 and my Canon 5D shoot video, but I almost never use the feature.
As for high ISO, I think the Canon 5D really spoiled me. ISO 3200 is really clean, and I wouldn't hesitate to go even higher if I needed the shot. Luckily, for underwater photography with the GF-1, I have a flash/strobe lighting setup, so I don't have to stray away from ISO 100.
One thing to consider about this camera is that it does not have in-body image stabilization like the Olympus. The Olympus though don't have the LCD that the Panasonics do. I wish there was a hybrid of the two camera systems with the responsiveness of the Panasonic LCD and AF system and the image stabilization of the Olympus bodies. Having said that, if you do buy the Leica 45mm, it has in-lens stabilization and you're good to go.