I saw a bit too. Each of them has two puppets, representing housemates, as there are 7 of them and there has been 14 housemates, that works out fine.

They cannot play themselves, so have to play each other!

Suggested incidents in the sketch are

Alex's constipation
Wee-ing in the shower
Sunita refusing to hide in the drawer because she is a qualified barrister

so it should be fun.

BTW Alex is being played by Jonny who does Alex's voice better than Alex does! If you know what I mean..