I would always wait for my garage door to close, if I had one. You can't be too careful. That video is somewhat scary. What if they weren't harmless, just-having-fun college-educated young women?? Security, codes, alarms, watching your back, neighborhood watch, and watch dogs are all very valuables things that homeowners (and apartment dwellers, such as myself; however, I live a secure building) should have(at least) to protect their homes and themselves.
The door between the house and the garage DEFINITELY needs to be secure.They should always lock it behind them.
Someone who knows them could probably send a copy of the video to the police and have them arrested for trespassing. It's crazy what some people are putting on youtube, as if what their doing is perfectly legal.