Its on total download amount not type. If you go over what they feel is a fair usage amount it will be capped.
It's both. They'll throttle a connection if it exceeds the download and/or upload limit.
File Sharing:
We also moderate the total volume of file sharing traffic on our network between 5pm and midnight on weekdays and midday and midnight on weekends. This policy, which applies to all broadband packages, is restricted to Peer to Peer (“P2P”) applications and Newsgroups (which are commonly used to distribute large amounts of data)
This policy does not impact any applications other than Peer to Peer and Newsgroups, so things like watching iPlayer, online gaming, making calls via Skype, downloading music tracks from iTunes or streaming them from Spotify and sending an email or normal browsing are unaffected.
It's important to remember that these traffic management policies only apply at peak times when speeds are most likely to be affected by people using more than their fair share. Outside of peak times we do not manage traffic.