After this murder he was convicted of murder and 4 counts of arson. He received a 21 year sentence of which he served 15.
Here's a photo of him at the time of his sentencing.
And here he is now!
The idea of Burzday being celebrated on his birthday came from a .gif someone made. This .gif is made of footage from the same documentary as the above video.
I don't remember exactly, but I think he was actually talking about people running to take their pills in prison.
And so... HAIL BURZUM! IT'S BURZDAY!