Of course you’ll have to rely on QoS 
I don’t know what is you’re upload speed but here it’s ~1Mb and if I start the torrent client, it can eat all of it.
Now… I never bothered configuring QoS myself so I wish you good luck 
A good start would to try lowering the priority of torrents using a port range…
Then maybe you can lower priority of http traffic (ports 80 and 443)
Or maybe ToS use a dedicated port range and you’ll be able to prioritize its traffic…
Can you tell me what port 80 and 443 is for? I’m sorry if I’m ignorant with this… but the rules I made in my QoS settings were just followed through a guide, but without knowledge of what they really do. When you said http traffic, are port 80 and 443 for sites or browsing?
Yup, port 80 is http and 443 is https (I’m assuming that youtube videos are loaded through http, can be wrong).
I’m not saying it would be the best idea by the way Lowering web traffic priority in order to lower youtube’s seems a bit ~insert whatever english expression that I don’t know of~
Thanks for the info, I guess I’ll have to experiment stuff… Woooo! I’m learning something!
Ahah, happy to see you enjoying this 
Just found an utility that may help you : http://www.slashroot.in/linux-iptraf-and-iftop-monitor-and-analyse-network-traffic-and-bandwidth
Just tried it, iftop gives you bandwidth used by source/dest port.
/!\ It’s a linux util so you may need a live cd/usb