The video accompanying this was removed, anyone has any idea what's going on?

So, like, what? Lower numbers are better?

I think this fails to tell the whole story for reliability overall, anyhow. I saw the original video, and this is just a relationship between bore and stroke and piston speed attempting to judge the assumed stress on the piston or I guess also the connecting rod and camshaft. That's only a (shaky) predictor of one specific avenue for failure. But ask any Chinabike rider -- the poxy engine on any given Chinese Honda clone probably will run forever despite, somehow, being made of melted down Mountain Dew cans cast in sand dug up from the beach outside he factory, cigarette butts still included. But it's all the other parts on the bike that fall off over time. Ditto with, say, BMW. I'm sure they'd make a perfectly reliable bike if they could only get the electricals to stay working for more than seven consecutive minutes at a time. Etc.

I don't quite understand the calculation. It seems to disfavor big-bore and high compression motors. Could someone ELI5?

The video that explains things, though not super well. Basically it a metric that assumes all bikes are made equally well... so kinda useless.

https://youtu.be/azUev9CRHZQ