I figured since Franks the out-of-towner shares so many nice Quebec highway vids, I'd chip in...
This vid only partially features a highway (the 720), but nicely demonstrates how one may use highways in Montreal to shorten already pretty short trips.
It's shot in 'real-time'
This is the fastest way from westmount to old port (highway allows you to skip through SOME traffic)
• Video Link
In this clip:
starts on sherbrooke, corner greene (westmount)
-right on atwater (cross downtown)
-right on notre dame (this is in Saint-Henri)
-right on greene
-right into 720
-through ville-marie tunnel
-exit saint-antoine (old Montreal)
-right on gosford (towards old port)
right on notre-dame (passes city hall, palais de justice, other law buildings)