(copy of https://bugs.chromium.org/p/chromium/issues/detail?id=849636 which turned into a hunt for another bug; see figures in the other bug)
This has continued in M68 and M69 but I see a quite sharp drop in the week of October 8th -- this might be related to some product changes on our side.
chfremer: can you take another look? I can't provide camera names, just overall stats.

original report
I am seeing quite an increase in getUserMedia NotReadableError on appear.in.

The overall increase comparing M65 and M66 is ~28% -- see gum-total.png
There is no (significant) increase in errors on non-windows.
Lookin only at Windows only shows a 38% increase.

Splitting this up further (gum-windows10) shows that the error rate does not increase on Windows 7 and Windows 8 but the increase on Windows 10 is  around 55%.

It is somewhat unclear what would cause this. There were no significant changes to appearins getUserMedia usage during that time. 

This might not be an issue in Chrome itself but maybe the new Windows 10 release changed something in a way that makes NotReadableError (which is a hardware error) more likely?