DVD - When westerners teach chinese ...

I give you my interpretation of the two sentences before the song :

那里是老外教国语

Here is what happens when westerners teach chinese

老外的腿上有很多毛呀

This Westerners have hairy legs (maoist influence maybe - see 毛 and the melody of the Internationale)

It comes from the mainland version of the HK movie 《春田花花同学会》 (2006).