Her videos appear to be tutorials that are pretty long, most of them 1 hour+: https://loish.net/tutorials/ It wouldn't take many views/month to use a lot of bandwidth, assuming her customers watch the whole thing.
That's perhaps not worth $3500/year, but I can see why she might need a higher end plan with such long videos. $25/month may not be enough to cover the bandwidth.
What's confusing, though, is that their pricing page shows the highest-tier plan as $75/month, which is $900/year and described as "Unlimited live streaming - 7TB total storage". There's also the next plan down, at $50/month ($600/year), described as "No weekly Limits - 5TB total storage". So I'm curious where the $3500/year is coming from.