Yep, there's a filter on all Bethel internet. Porn sites are on the blacklist and all apostate sites, I actually tried visiting this site once and got a warning (and was never questioned about it, all I had to say though was "oops i clicked the wrong link, the URL was too similar to our official website, etc."). Basically you just get a blank page that says "Site forbidden: [reason, e.g. porn, apostate site, etc.]" and have to go back. However, your history is saved on the WT's servers and the Computer Department reviews your history every few months (or weeks). Also, I used torrents and other file sharing sites and never got in trouble.
If you're found to be looking at porn, the Computer Department tells your overseer. You are then summoned to meet with your overseer, who will question you over why you're looking at porn. The branch committee will then decide if you get to stay or not, in 95% of all cases IMO you're kicked out. Old man Max Larson (former printery overseer in the U.S.) supposedly said during a morning worship session that in the U.S., there's at least 2 cases per week of someone at Bethel getting caught trying to or successfuly viewing internet porn (by somehow bypassing the filter), and one time there were 7 cases in a week to deal with or something like that.
So there's lots of horny guys in bethel. Also, the WT's IPs actually say they're registered to the WT, and there was an internal letter about how you should keep that in mind when using the Internet at bethel.