Bug overview description.
Thumbnails for WebM-files with size ratio < 1 (tall ones) are constrained to 150 pixels wide, with most likely no limit on height. This is probably a very minor bug, since most WebM-files will have a ratio >= 0.75. Not to mention that they are

What part(s) of the site page(s) are affected?
Thumbnails

What is the expected behavior?
These thumbnails should be (a maximum of) 150 pixels tall.

What actual behavior is given instead?
These thumbnails are (a maximum of) 150 pixels wide.

Can you reproduce the bug every time?
Yes

What steps did you take to replicate this bug?
Check any thumbnail sizes in type:webm ratio:<1