It ONLY affects jumping. Using the Command Menu you can use a variety of Radio Commands that audibly broadcasts a message to your entire team, a very useful thing to have instead of typing. You can also use the Command Menu to change your team, your class, your weapons selection, or check the Capture Point Status menu. If timelimit is hit before a round is over, the round will finish before changing levels. Allows players to switch teams after warm-up time.
Spectators can talk to Players currently playing the game.
Change to 0 for better performance. Allows you to go prone and get up again. When you go into water you automatically go un-prone. Allows you to change your team. All the radio menus can be accessed from the Radio menu.