Its so unlikely at a "single" provider can cause an internet meltdown. However, the STREAMING sites may not be able to handle the client traffic, or companies LAN could fall under the weight, due to employees watching. But a world or national (US) Internet melt down is probably very hard to create, and the FIFA World Cup won't do it.

The colo that is doing the streaming is much more likely to have issues, than the "Internet" as a whole. And I figure there is more than 1 server, in more than 1 colo doing this. Yes, for some, it could be slow, or they can't connect ... but that is just for that site, not the "Internet".