I'm sure there will be an audition show sometime on C4 this year but before BB10 started, there was a small section about the welsh auditions on Uned5 on S4C.
http://www.s4c.co.uk/clic/e_level2.s...e_id=340576205
It is all in Welsh but you can use the subtitles (second symbol in on the right)
Its about 30mins in (half way)