Apple had spectacularly bad timing
The problem modern video - and many multimedia pipelines - is that it's much more CPU specific than you'd think.
People assume that the work is just offloaded to a GPU, and for much of the video encoding/decoding that's correct. But for things like audio processing and some graphical effects, the CPU multimedia extensions are used. Stuff like MMX (remember that?), 3DNow!, SSE, AVX.
In my own experience we've been avoiding deploying any M1 Macs at my workplace because the noise cancellation in Microsoft Teams relies on Intel CPU instructions - so the option just wasn't there on M1 Macs at first. The x86 instruction set emulation is great, but only covers the core features of the CPU.
(Native noise cancellation on M1 Macs is now in testing from Microsoft, but we'll hold off until it's stable. We don't need Teams crashing on Macs due to this, especially as those with Macs are more likely to be in a position where their meetings are a bit more important.)
None of this is unsurmountable. It's also completely understandable - I'm not blaming or slating Apple for this. I'm just saying that it is, in many ways, the worst timing that they could possibly have had. The M1 Mac that couldn't cut it for our correspondent wasn't a bad machine, it was just that the software isn't yet optimised to use it. In a way, Apple's excellent work at compatibility gave him unrealistic expectations.
Further to that, on Windows you can definitely expect those multimedia extensions to be on any modern CPU, so all the software is using it. It's not so much that it comes from a gaming background (which it does), more that there are very safe assumptions you can make about what hardware features will be available to any PC running gaming software. Ironically, the same software ported to an old x86 mac might have done much better.
Apple - and the ecosystem of software for their computers - will no doubt get there. But a CPU change right before a pandemic really hasn't helped in this particular use case, and serves as a reminder of just how complex computing is these days, and how many edge cases there can be.
(Note: I am not a huge Apple fan. They have their strengths and weaknesses, but I don't personally use their kit and I find them more problematic to support in a business environment than Windows machines. Please don't assume I'm a fanboi, I'm just trying to point out that Apple's compatibility efforts can only go so far, and that is probably why Mark's attempts failed. I shall make my true loyalties clear with my choice of icon...)
Biting the hand that feeds IT
