Your pronunciation is generally clear. One thing I noticed, though, was that you don't distinguish between /i/ and /i:/. You pronounced 'witch' as 'weech' and 'trick' as 'treek', for example. That needs working on.

You also need to work on a more natural intonation and prosody. You should try to stress the important content words and weaken the less important ones, and separate what you are saying into 'chunks' of meaning, marking the separation with a slight change in tone and a slight pause. This will make your speech more natural and easier to understand.

Is it more British or American? Neither, really. You just sound like a fluent non-native. I noticed a few American influences, while an American would probably notice the non-American features and think you sounded British. And it doesn't matter. You have your own accent.

My pronunciation

It's a very good effort. As a general comment, I think your delivery would benefit from being a little  slower. I'm unsure if at 0:12 you say "It is celebrated by 'a' many people in the United Kingdom" ?