What is this glitch? can someone link me a video of it?

The glitch is easy. Like pubs said,it's all the timing.

It took me and a friend over 4 hours to get the 1st car in. One thing we found out is everyones timing is different. Depending on your connection and what car your getting into. So just doing what someone else is doing may not work for you. Use the same car every time and keep track of your timing. Hit Y then hit A as soon as you grab the door handle. Next time hit Y then hit A just as he opens the door. And keep track of when your hitting your buttons and where its spawning you. Youll get it soon