Google Pagespeed Insights downloading both webm/mp4 formats (Avoid enormous network payloads)

Provide the steps to reproduce

Use the tool at https://developers.google.com/speed/pagespeed/insights/ to measure an html page, where a similar code exists:

<video width="1800" height="700"  preload="auto" loop autoplay muted>
<source src="https://domain.com/home.webm" type="video/webm">
<source src="https://domain.com/home.mp4"  type="video/mp4">
</video>

What is the current behavior?

It downloads both the mp4 and webm formats (Google Chrome doesn’t do this, so it’s just an issue with the pagespeed insights tool). It triggers the “Avoid enormous network payloads” recommendation. http://prntscr.com/nk8hx3

What is the expected behavior?

It should only download the webm format and skip the mp4. There should be no “Avoid enormous network payloads” message, unless needed.

[geeworthington]

This issue/bug is still apparent.

I have a video running in the background / banner of my website homepage and I have two versions. A webm and an mp4. Google insights is detecting and penalizing my score (triggering the “Avoid enormous network payloads” warning) as it is downloading both?!

Has this bug resurfaced? Or am I doing something wrong that is blindingly obvious?!

I have almost idential markup as @peixotorms

<video loop="" autoplay="" muted="" playsinline="">
<source src="https://mysite.co.uk/myvideo.webm" type="video/webm">
<source src="https://mysite.co.uk/myvideo4.mp4" type="video/mp4">
</video>

Thanks in advance for any replies

[connorjclark]

If you are still seeing this: please open a new issue and fill out the bug template. Most importantly, pleases provide a URL.