I mainly use Jaksta to download tutorial videos on youtube so that I don't have to find them again if I need to reference them. I have noticed that on some videos, the ad will download with audio, but the video file itself is lacking the audio. Usually, I have to keep refreshing the page until Jaksta finally gives me a video file that has the audio, but it's annoying to have to repeatedly refresh the page until I can get the complete video, plus it doesn't always work. When the video files have no audio attached, the file has '299' appended to the end of the name. I tried deleting the old app and preference files, rebooting the system and doing a fresh install, but with no luck. I also tried the beta I found in this link, but this did not work either.
I did some testing on the video/stream that comes up in your log file and experienced no issues.
However, your log file does indicate some inconsistencies that suggest an issue, which could be universal or specific to your system.
I have passed your enquiry and log file onto development for them to have a look, and will let you know when I hear something back.