yes I live in US now and canada ( before ) and I travel to UK a few times. I agree that American love to express themselves and Canadian is pretty friendly :)
You two are perfect match for youtube videos. Faye speaks like a DJ, and Stevo adds in a lot of humour. A Westerner speaking good Cantonese draws a lot of attention! Well done and keep making good videos for us!👍
I had a similar experience at Luton airport several years ago. My wife and I were returning from Amsterdam over weekend in the midst of our overseas attachment at Oxford. A lady border official stopped us and questioned us for working in the UK without a valid working visa (we were not on a paid job anyway). But that should be just a rare incidence. My overall impression of UK borders is very good. They are helpful and efficient in general. On another occasion, we were on a tight transit flight back to Hong Kong. The border staffs actually fast-tracted our inspection and allowed us to get to connection flight on time.