I watched till the end
As I said, no music would be better for continuos gameplay like that, so we can immerse ourselves in the game sounds, hearing distant firefights and everything else is much more fun imo. For a video compilation, where you have multiple fast scenes glued together, some music can be what unify them all, so it's not that bad. Well music is fine, but in your video it could be lower imo, so we can hear the talking better, and any music style will never be enjoyed by all viewers.
About your actions in-game, some things I noticed:
1. Sometimes you are not going for the same things your squad is going for. The SL puts an attack command and they start shooting and you are running to the other direction. Try to be more alert to what your SL is marking.
2. Lots of times you are running and shooting, rushing towards your enemy. It may work against one single enemy, but against multiple targets it will only get you killed (as it happened in the video). Being in a position you can fire but get into cover when shot at is much better.
3. You don't need to use the medic hands multiple times, usually only once is enough. Saves time
4. Try to talk less, only passing important information.
Anyways, those were some issues I noticed in that video. About the "sniper rule" you asked, I'm not sure what you mean. If it's how many seconds you have to wait before shooting, it's really not an exact science as it varies from player to player, server to server. I was getting some fast shots simply because I wasn't moving and not moving my camera too fast. That's usually enough to get some shots on target. Wait for him to stop and get some seconds of breathing to get a good shot. Sometimes it will not work, but some it will.
![Wink ;)](./images/smilies/icon_e_wink.gif)