Good practice. I know those logs are slimy.
I'm REALLY glad you didn't break your arm or wrist though. At 2:10 in the video, it's visible that the right bark buster is way to high. Those should be pointing slightly down, just for that reason, so you're hands are less susceptible to getting trapped in them when you're thrown off the bike.
They're a double edged sword. They'll keep your hands and levers from getting busted on trees while hauling the mail on tight single track, but that other thing can happen.
If you had actually gone over the bars, it wouldn't have ended well. You certainly wouldn't have been the first, there are plenty of horror stories.
Keep at it though. That's some good training. Please lower those guards a little.
The story of three wheels and a man...