Why would he mention "pro" before the "tip" in this context?
Native speaker’s answer
Rebecca
Here, "pro" describes the kind of "tip" it is! "Pro" is short for "professional," so he's saying that it's a professional tip. Ex: Pro tip for a great curry: cook the spices in some oil first. Ex: Pro tip, make sure you don't paint to the edge of the page, then you can trim it nicely.