What kinda tin whistle is he using?

[Biathlonman]

The tune is pretty easy - but look and listen to how he puts ornaments on every note. Held notes get a vibrato treatment in case the whistle is slightly out of tune, and he rarely goes from note to now without adding a little turn or ornament here and there.
Any one of us could learn this - it isn't hard. What is difficult are tunes when you have to play complex fingerings fast and correctly - but this stuff in the video is kid's stuff. Try to copy him.
Biathlonman (and a veteran of sitting in bars with a fiddler playing easier tunes)

[OC Richard]

Well I watched that video and seeing as how the top of the whistle is hidden by the microphone and the bottom of the whistle isn't seen either, one can't tell what kind it is. (A Clarke would be very narrow at the bottom.)

In 1983 Clarkes were only made in C. For all other keys it was Generations. Many traditional players at that time preferred the Clarke C over the Generation C. The Feadog D was introduced around that time as I recall.

What key is he playing in? I could find out by playing along but it's 5am here and everyone else in the house is asleep!

Today, unlike in 1983, there are dozens and dozens of whistle makers and a whistle player today has a huge number of choices. I still like the old-time sound of Generations, of good Generations that is.

I still play the Generation C I bought in the late 70s and the Feadog I got in the early 80s. I still have a Clarke from the 70s but I've never been a huge Clarke fan.

By the way Liam Og there is playing sharp half the time! Really jumps out nowadays, when we're used to everything including pitch being fixed in the studio.

[Pyper]

To me it appears to be a straight bore whistle. It does not appear to be nickel plated. To me, it really doesn't look like metal, although it could be heavily tarnished brass.

It might not be a mass produced whistle.

He does have a great tone. One thing to note though, is whenever you hear a whistle played through a microphone, there is a possibility of tonal alteration -- not just because of the microphone, but the sound man may dial in some EQ or compression, or whatever.