The Science of Wine and Cherry trick

When anything burns it takes oxygen out of the air and combines it with other elements to make slightly more complicated chemicals (such as water or carbon dioxide). These elements are more dense than the oxygen gas and so take up less "room".

Normally you would not notice this, as other air rushes in to even things out, but when the glass is put over the top of the burning matches, it stops any air getting in. So, the pressure inside the glass gets lower. In order to balance everything up, the air pressure ouside the glass forces the wine inside.

The cherry is just there to make sure the matches float and don't get put out by the wine!