It was a silly video, but I don't think he's intended to incite hatred or be pro nazi. He's just made his girlfriends dog sieg heil in order to wind her up, and I think that's as far as it goes. If anything, he's mocking nazi's with the video. As Pie said, context is important and the fact the judge and prosecution have said it isn't is kind of terrifying. I certainly don't think he should go to prison for it, and hopefully he won't
This case does set a precedent though
How long before people are getting arrested for "grossly offending" people because they hold a different political or religious opinion to them?
The start of a slippery slope I fear