The best advice is to try them all. We've verified that they all work when putting them together, but they don't always work during air and several visitors give conflicting reports on reliability so your best bet is to try them out for yourself!
If none of them work, please don't moan and get angry in the shoutbox. There's nothing we can do it about and it's just distracting and off-putting for those people who it does work for..
Sadly not as all the players use Adobe Flash.
Sadly, this could be any number of things on both your side and the servers side and we have practiclly no control over either side.
Things you could try involve refreshing the page, restarting your browser/computer, manually clear your cache, reset your ip address.
The Christmas special will air on Christmas Day (25th December).