Effective autoplay block

Hello everyone,

I know there are settings in Firefox that are supposed to block or prevent 
automatic playing of audio and video content in web pages and I have set all 
the ones I can find to block such content.

But still I see and hear video and audio content on some pages playing 
automatically without my permission!

Is it really impossible to make prevention of automatic playing of audio and 
video content:
- easy to select, and
- effective?

If it's not impossible, can we PLEASE have easy and effective autoplay 
prevention?

Can these settings also prevent automatic downloading of audio and video 
content?

R.