I asked this very same question a long time ago with the same sort of answer. People who do know won't tell you, people who have guessed won't tell you if it is guessed correctly, and people that will tell you are probably wrong.
Through multiple watches I also came to the conclusion that actors where involved. I believe Dynamo uses a lot of actors to accomplish the magic he does. This isn't a bad thing as it creates a great show for laypeople, however it leaves magicians like us chasing dream effects that in the real world can't happen.
I'd suggest doing a coin in bottle or cap in bottle or something that is actually possible, as i believe that with a glass bottle this is not.
Simon_Magic