I can't speak to those posting on YouTube, but NOBODY with adequate internet, especially 100 mbs download speed, suffers buffering due to low bandwidth. For one, no service is streaming at that rate.
Buffering is almost always a streamer side issue. A bad setup on the user side could also cause problems. Or 50 people on the same network streaming at once. Also some IP's cap bandwidth. Here's a link with Netflix recommendations:
https://help.netflix.com/en/node/306
At 4k/UHD you only need about 25 mbs, 1080 uses around 5 mbs. Having 100, 75, 50 mbs doesn't matter in regards to a single stream. Much like those YouTube posters, I'm just some random dude on the internet. But while relatively new in the iptv arena, I'm not a novice in audio/video. Like ThaTopMoron above, I've been downloading HD video/lossless audio for years (file sharing moreso than torrents). Have a large movie/music doc/concert library set up through Plex, with a Nvidia Shield for various apps and iptv. All ethernet, but even with wifi I rarely have any buffering with Netflix/Amazon, etc. Occasionally get a glitch streaming a game on ESPN+, but like I said that's server side. While not always as reliable as cable/satellite it's damn close. And if they don't want to offer me the option to purchase the nfl ticket, etc., then I have no problem spending a fraction of the cost and watching whatever the fuk I want