You have to watch for a little while, but here's what happens:
1. Celtic scores rebound goal.
2. Scottish announcers have an unintelligible conversation about said goal.
3. Celtic supporter runs onto pitch and viciously assaults Milan's goalkeeper.
3. Fan runs onto the field, touches goalkeeper, goalkeeper gets sand in his vagina and falls down.
How does this NOT remind you of Pitt football? I mean seriously. Both found the fetal position at the first sign of danger.