Sorry for the links to hellsite, but:

Here's a video of a masked mob going down a Belfast street, trying and sometimes succeeding in breaking down doors to get into houses of suspected immigrants. And here's one where they set a vehicle on fire and sent it down the street.

If you google for more Belfast videos, make sure to specify something like "mobs", "fires", "riots", etc, as the video of the second stabbing is fairly prevalent online.

The Wikipedia article is getting updated regularly, but is obviously not as polished as events are still evolving.