I have been concerned about the same thing. My best guess is that the first to be effected is streaming video and netflix etc etc. These are direct competition to my local ISP/cable provider. Not sure about youtube. This could be bad for them.
Not sure about trading. Possibly news feeds could be throttled unless they pay the ISP. Perhaps the ISP will have a prefered brokerage and all other will be throttled. That last one seems like a lot of work for ISP s with little gain.
Its likely to be very good news for smaller local/independent ISP s. If people are unhappy with the local cable company controlling thier content there will be a market for unrestricted net access.