I know the Alt trick and sorting. However video thumbnail generating is too slow, and my video file are scattered everywhere, so each time I do importing and want to see thumbnail for my latest photos I have to wait 10~20 minutes for video thumbnails being generated first (1~2 minutes for each).
And I don't process video at all in lightroom (and it can't) so waiting for video thumbnails is ridiculous.
The current solution is to view photo thumbnails in explorer (with help from Microsoft camera codec), memorize file names and then select photos in lightroom without thumbnails.
I have no idea why video thumbnail generating in lightroom is so slow. Icaros can generate video thumbnails instantaneously (directly from card), and my cards are at least uhs-1, combined with usb3 card reader the read speed is at least 80MB/s. Also I tried disabling smart preview and changing preview size though they should only affect develop, and performance has not changed.
Not to mention lightroom fails to generate thumbnail for about half of my video files after tedious waiting.
for video thumbnails being generated first (1~2 minutes for each).
Something bad is happening with your configuration -- in general, LR generates video thumbnails reasonably quickly. You could repost all your information at the official Adobe feedback forum: Photoshop Family Customer Community . Be sure to include the exact version of LR you are running (do Help > System Info rather than relying on memory) and version of Mac / Windows. Adobe product developers read every post there and sometime reply, whereas this forum is primarily user-to-user.