I've been slowing learning the imperial measurement system and I would say that it's now natural to me in a very limited sense.
I grew up in Australia using the metric system. As a child, it was (and probably still is) common to throw around estimates in inches or yards, but anything precise was expressed in in mm or meters. So I've always had a sense of how big and inch or two is but like the presenter, for anything bigger I'd need to perform a quick conversions back to my natural metric measurements to understand what was meant.
I'm also a woodworker and use many vintage tools, produced before the world adopted metric. I decided long ago that I would these tools as they were designed to be used and not try to mess with metric, too.
At the time, I had no intuition at all about fractions of an inch. I didn't even know that 8ths and 16ths where how they were divided. I literally had no idea. I needed to pull out my maths brain to tell you whether 7/8 or 5/16 was bigger.
I used imperial measurements almost exclusively while woodworking in my shed. This was possible because I don't need to communicate measures to anyone other than myself. I also don't often need to take measurements of odd things that don't fall nicely onto an imperial ruler.
I'm now comfortable using inches for measuring things up to maybe 100" — I wonder if 100 is only an obvious stopping point because of my metric upbringing — I still have no concept of a mile or yard before converting to metric.
But I do still do use metric when I need a precise measure of something that can't be expressed easily in inches. So I'd use 12" rather than 304mm, but I'd use 300mm rather than 11 and whatever inches.
Also, it's made easier due to a lot of hangover in stock wood dimensions. It still comes in thicknesses that are more naturally expressed in inches, for example 19mm (3/4"), 25mm (1").
I've been working this way for about 10 years and can now think in inches without any conversion. I doubt I could flip all units of measure to imperial without changing the world I live in and the people I work with.