7Gbits/s saturated over a month is 2,247 TB

http://www.google.com/search?hl=en&q=7Gb%2Fs+in+TB%2Fmon...

So at your €15/TB i would be €33,705 / month

Also €15/TB seems low as prices around the US are $0.10/GB so $100/TB which would equate to around $200k/month

Of course when you are pushing that much data you're going to want to pay per Mbit/s and with bandwidth as low as $3/Mbit we get around $21,000/month

What is probably happening here is that this guy has 7 dedicate servers at about $150 each per month that have a gigabit connection with say a couple of TB data allowance for each server and he's just saying that he has a capacity of 7Gb/s. The chat client is probably peer to peer so the video bandwidth for him is not that critical.