It's his first ban on record. Usually first bans are 1 hour or even 30 minutes when given while the player is on it in game, depending on which rule the player is breaking.
First bans given from ban requests on the forums are more than 1 hour, making it more possible for the player to actually see that he has been banned for breaking a rule. (Since the player might not be in-game when the ban is set.)
So the first bans are from 2 hours to 1 day, when given through a ban request. Depending on the heaviness of the players actions.
In this case, this player was blocking you and one other CT from reaching a camping spot. You fell off twice, then managed to get past the blocker, then went down again on purpose to make it clear that he's also doing the blocking on purpose.
His actions didn't cause too much harm to you or to the other CT, you took like -10 damage by falling off high, so that's how I judge this ban and its length.
If he kept on blocking you till zombies came to your room and got you infected, I would have given the player the maximum ban length he can be given for his first ban with the reason Blocking. (1 day.)
But because the blocking was harmless, and you managed to get past him, I made the decision of giving him 4 hour ban.