Hand from $5000 Pot limit WSOP event

[SoBeDude]

My friend played this and asked me to post it here.

First hand of the event. Blinds are 25/25. 5000 starting chips.

2 folds and he raises to 100 with AQc.

just the BB calls (Chris Bigler).

Flop comes QJ5 rainbow. Chris checks, he bets 200, Chris calls.

Turn is another Q, completing the rainbow. Chris checks, he bets 500. Chris now check-raises to 1500 quickly.

My friend thinks for a second and calls.

River is a 7. Chris bets out 1500. Whats my friend's play and why?

-Scott