How to throttle iPlayer?

Whenever I have iPlayer downloading on my PC comes down nice and fast but it uses the entire bandwidth. I can barely browse basic webpages and other users start asking if the internet connection is down.

I heard about netlimiter but I'm a bit wary of that getting detected as a cheat or whatever in online games (people abuse it because lagging out on command can be advantageous).

I'm wondering if the router might have something to do with it. I never used to have this issue before but I only use iPlayer extensively enough to notice every now and then, and we changed router a while back when Sky bought out Be. Hoping to avoid having to buy something though, since it's just an occasional problem and the Sky router otherwise serves well enough.

Downloading video to play back later or streaming it?

Downloading for later viewing via iPlayer Downloads program

Ok so no different from any other big download, in which case any router with some QoS support my help i.e. could throttle down the device using iPlayer to leave more headroom for every one else

Thanks!