I'm no expert but I would think that your line can handle 50/10 maximum meaning that if you watch TV you won't have the full 50/10 available for Internet but more into the 25/10 rang.
See following link to Bell website under the section "What happends when I turn on my TVs." it somewhat confirms me theory. »
fibetv.bell.ca/en/internet/Other Fibe Internet clients confirmed having their 25/10 bumped up to at least 40/10 for free once their subscribed to Fibe TV.