LPS-39361 import previews

Hi Alex!

@KocsisDaniel told me to send you instead, because it was a DL only change.

BTW, I saw here: https://github.com/brianchandotcom/liferay-portal/pull/14734 (LPS-41103) that could cause the same for previews. I tried to reproduce but I couldn't. The solution would be very easy anyway.

EDIT: See my last comment. I could reproduce using remote staging and video files.

Thanks!