Most of the files in the /opt/kaltura/web/content/entry/data/0/0 folder are apache:kaltura with permissions set to 640 (including the latest jpg from the video upload). There are a few older ones that are set to kaltura:kaltura with permissions 664.

When viewing the main KMC entry page, I see an error like this:

2016-09-14 12:09:39 [0.000288] [129.128.36.159] [247136258] [45] [PS2] [KExternalErrors::dieError] ERR: exception 'Exception' with message 'exiting on error 17 - image resize failed' in /opt/kaltura/app/infra/log/KalturaLog.php:83
Stack trace:

0 /opt/kaltura/app/alpha/apps/kaltura/lib/KExternalErrors.class.php(128): KalturaLog::err('exiting on erro...')

Sometimes I also get:

2016-09-14 12:11:09 [0.000385] [129.128.36.159] [1118263185] [43] [PS2] [KExternalErrors::dieError] ERR: exception 'Exception' with message 'exiting on error 11 - processing capture thumbnail' in /opt/kaltura/app/infra/log/KalturaLog.php:83
Stack trace:

0 /opt/kaltura/app/alpha/apps/kaltura/lib/KExternalErrors.class.php(128): KalturaLog::err('exiting on erro...')

But I'm not sure if it's as relevant. The thumbnail definitely exists and I can even download it via the KMC.