I guess that's one way to wash your glassware

That's my upload of a video I originally found here (warning, adult word in the link - video is school-appropriate, though).

So, what's happening here (I think)...

Clearly, something is burning. I don't see any fire, but the lighter lights 'something' inside the beaker. Because the fire is 'invisible', I'm assuming the inside of the beaker is coated in methanol. It might be ethanol or some other alcohol, but the fire isn't visible enough for me to think it's anything else.

The vapors burn, momentarily heating the inside of the beaker and pushing lots of gas out. Depending on the stoichiometry, it also uses up more moles of gas than it produces. If the water vapor then cools quickly enough, there's an even greater drop in moles of gas.

If the moles of gas inside the beaker decrease and the temperature decreases, the pressure is going to drop. That lets the outside air push the blue water into the beaker.

It's sort of like the ammonia fountain or the can crush demo, but this drop in gas moles is due primarily to combustion and temperature changes (I think.)

All that being said, the idea of igniting methanol vapors just seems stupid.