No repro on 71.0.3558.0 (Official Build) dev (64-bit) eve.

Same, no reproduction eve 71.0.3558.0

rkalavakuntla@ Official release chrome-os devices should be able to play an MP4 video.  Can you confirm that your device can play MP4 video?

C#5 >Yes,able to play MP4 videos on the priority chrome-os devices.

Repro'd on eve 71.0.3558.0.

The image loader had this error:

Video thumbnail error:  Error: Seeking video failed.
    at Promise.race.Promise.then (background_scripts.js:2815)
(anonymous) @ background_scripts.js:2770
Promise.catch (async)
ImageRequest.downloadOriginal_ @ background_scripts.js:2769
ImageRequest.downloadAndProcess @ background_scripts.js:2631
(anonymous) @ background_scripts.js:3245
(anonymous) @ background_scripts.js:1408
dataRequest.onsuccess @ background_scripts.js:1433
IndexedDB (async)
ImageCache.loadImage @ background_scripts.js:1386
ImageRequest.loadFromCache_ @ background_scripts.js:2665
ImageRequest.loadFromCacheAndProcess @ background_scripts.js:2614
Scheduler.continue_ @ background_scripts.js:3242
Scheduler.add @ background_scripts.js:3178
ImageLoader.onMessage_ @ background_scripts.js:1879
ImageLoader.onIncomingRequest_ @ background_scripts.js:1854

And the culprit seems to be data saver causing preload = 'auto' to be ignored: https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/html/media/html_media_element.cc?l=2353&rcl=dc14201567f60c97163c61df182601df636d2a03 if the right experiment is enabled. I guess no one remembered filesystem URLs exist.

For extra fun, it looks like it forces preload = 'auto' to preload = 'metadata' when on cellular, even for blob, data and file URLs.

This issue is marked RBB, beta is coming soon. CC'ing a few people to help find an owner. Thanks

+tbansal@, +mlamouri@, 

The most recent change to that code looks to be this by tbansal@
https://chromium-review.googlesource.com/c/chromium/src/+/1046145

But that would have shipped in M68?
https://chromiumdash.appspot.com/commit/333819e9e8ebff5f4d62842accbcbe97e43f160e

I agree we shouldn't override 'auto' for blob/data/file URLS, so thats good to fix either way.

Separately, I don't think this feature should rely on preload='auto' - auto is up to the UA and the UA decided not to :). If you need the first frame reliably it makes sense to explicitly load() the media. 

I don't the file browser code at all, not sure where to implement that last suggestion.

Can this be repro'ed in M-70 or earlier? Data saver has ignored auto preload for a long time. Also, does the repro works if data saver is disabled by the user?

 This issue is marked RBB, beta is coming soon. Can you please provide a status update? Thanks

I verified that this behavior is observed when the user has installed the data saver extension. However, it's not a recent change. I was able to repro it on M-69 stable, and it has probably been there since a long time (likely M-53: See  Issue 607551 ). 

The CL referenced in c#11 is for an experiment that changes this behavior. i.e., when the experiment is enabled, it decouples the media stack preload logic from data saver state.

> I was able to repro it on M-69 stable, and it has probably been there since a long time ...

Removing RBB

> I agree we shouldn't override 'auto' for blob/data/file URLS, so thats good to fix either way.

tbansal@ can implement this change?

Also adding kaznacheev@ - looking for someone more familiar with the ChromeOS UI code. As mentioned above, relying on preload auto is a bit fragile. 

Let's move this to M72 given we are past branch for M71.

> I agree we shouldn't override 'auto' for blob/data/file URLS, so thats good to fix either way.

Assigning to tbansal@. 

I don't think I can help here, this is not really my area. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/145b9f4d95dc1afc73835c8877b24d0a8c631d9d

commit 145b9f4d95dc1afc73835c8877b24d0a8c631d9d
Author: Sam McNally <sammc@chromium.org>
Date: Fri Oct 26 07:02:05 2018

Explicitly call load() on video elements when generating thumbnails.

The image loader used by the Files App relies on setting the preload
attribute on a video element to trigger it loading some content to use
as a thumbnail. In some circumstances (e.g. data saver), preload is
ignored for video elements.

Invoke load() on the video element explicitly to ensure it loads the
video.

Bug:  888962 
Change-Id: I2114bbb36feac3eafbb90cae2babd67d93247a25
Reviewed-on: https://chromium-review.googlesource.com/c/1301053
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603012}
[modify] https://crrev.com/145b9f4d95dc1afc73835c8877b24d0a8c631d9d/ui/file_manager/image_loader/request.js

Is this fixed now?