ok that is a bit weird, maybe the channels are external, some of them is.
I am not the biggest sports fan, but some of my friends are hence the champions league nights also watched HBO events, and I do watch some boxing events though, and other stuff mostly on the request of my friends who are computer illiterates.. could you try pm'ing me before hand when some big events are happening on these channels and we can compare directly? I am naturally curios, its in my blood heh. and I am not disregarding what you are experiencing at all.
the internet is very unpredictable, and some of what you see happens for me too the other way (to US, Canada, and Australia which has paticular bad infrastructure though).
an example of how unpredictable the internet is if I trace route to iks66.tv, rocket , or nfps.
I am (very lucky) and goes trough minimal of 5 hops (I wont post the hosts I go trough but you can always try pm)
my localnet, my public ip on my isp's net, the ix of my country, amsterdam ix, iks66.tv server. 1,2,3,4,5 very short - cant be shorter.
with a average ping time of 17ms!
if I trace route aftvnews.com I go through 7! hops of isp's in my country, before I reach US then 4! hops through US isp's, I then hit the aftvnews server.
with a average ping time of 115ms
in this case it completely disregards my direct connection to the IX, and takes another route, now this route could/should be faster depending on the other isp's so there is some reason behind it. but if the other isp's are cheap and allow for to many users or cap them at primetime it will be slow(er). and the same thing applies on the other side of the ocean. other US sites take other routes and directly to the ix, it differs.
I know this example does not mean much in praxis, but there are far worse scenarios for me too.
but it proves how inconsistent things can be, I happen to have faster connections to the rest of Europe and worse going overseas.
and nfps,rocket,iks66 even though located in belize, they do not use the caribbean IX (I dont think many do yet if you search the internet), instead they seem to have bought their hosting and connection at a company connected to the amsterdam IX that offers offshore hosting. I am of cause not completely sure of the details, but it looks that way.
but as said next time you there is a live event you expect to buffer feel free to pm me the channel no. and the event before its going on. as said I am curios at nature, things bite to me and I am a stubborn troubleshooter.