That’s Graham Norton’s set, so some googling reaveals that she’s someone called Cheryl Cole. Here’s another image of her from the intrenets.
So she’s got normal legs, and seemingly not rickets.
Here’s a clip of her in the show, but you can’t see her move her legs - what you can see is the arrangement of her leg and skirt moving.
http://www.bbc.co.uk/programmes/p021bzrz
1 - She has a skirt with a cut up to her hips. It’s down to her knee, and curling over her thigh - that’s the main cause of the confusion
2 - She also seems to be quite thin, so muscles are fairly well defined, so her thigh has definition (I believe that’s the correct word)
3 -There is a shadow cast by the skirt obscuring the top of her thigh up to the top of her knee.
It does look really weird, but it’s just shadows and fabric.
