Sorry about the delay, I didn't quite get all the way through testing yesterday before I left. I didn't turn up too much unfortunately. I like your thinking though, it does seem as though it might have something to do with the cache.
/opt/kaltura/app/alpha/apps/kaltura/lib/cache/ is set to 755 with ownership root:root. I tried flipping to 664 with apache:kaltura, but this generated a number permission errors with kaltlog running. Setting to apache:kaltura won't harm anything, but it seems it needs the execute flag.
/opt/kaltura/app/cache is set to 775 with ownership apache:kaltura (little less restrictive, so I didn't change)
/opt/kaltura/app/infra/cache is set to 775 with ownership root:root. I didn't try changing this one after the first path threw some errors.
I flipped the log verbosity to 7 using writers.stream.filters.priority (then setting .name .priority and .operator) according to how it was done for other log files. I restarted httpd, wiped out the log file, accessed a video (so the error 17 was thrown) and checked out the log. There are a lot of debug prints, but I didn't find any that mentioned returned value. All told it ran for 5 seconds, but it generated 300 KB of data, so I think the verbosity was changed correctly.
I can send you the log file if you'd like to take a look at it.