BUG: interferes with Brightcove media player on latest version of Firefox

[CDUpchurch]

Brightcove Player Version | 6.64.2
Windows 10 Pro (4-bit)

Before adding the Firefox add-on, this media player was working fine.
Added duolingo-tts-controls to FF (latest version of each). No other changes during this time.
Brightcove no longer displaying video, but I could still hear audio. Cannot use a different media player, because the content I need is embedded --using Brightcove-- in an educational website that I need to use.

Disabled this add-on ONLY (left all other FF add-ons enabled).
Brightcove is working fine again, now (with duolingo-tts-controls add-on enabled, no other changes on my PC).

Not a programmer or coder, so I have no idea why this media player and this add-on don't play well together.
Good luck!