Creating tooltips for video and audio

Add-ons Development
#1

I am trying to create an addon that converts the tooltips of the toolbar menu ( e.g download, close tab etc) from text to speech to aid visually impaired users. I am also trying to add short pre recorded sign language videos as tooltips for these icons to aid Deaf users.

I am able to locate where these tooltips are located within the source code and where the text is printed in the source code and I am able to modify this text to speech and video. It seems as " tooltiptext" is already predefined as text… I am struggling to convert this text to speech and video. Should anyone please assist on how this could be done?
Essentially what Im trying to do is create a mouse over/ mouse off tooltip for audio and video for the icons in the mozilla firefox toolbar menu

I have downloaded the source code.

#2

Barrier-free software is always a good thing. I see a few practical issues, however:

So your deaf users are analphabetic but know sign language … ?

create a mouse over/ mouse off tooltip for audio

How is a blind person going to aim for a button in the first place? If the user isn’t blind but ‘just’ visually impaired wouldn’t very large tooltips work? That would be much easier.

Anyway, if you do want to see how TTS could work in a browser, I’d suggest you have a look at some of these extensions:

https://addons.mozilla.org/en-US/firefox/search/?q=tts