Your test is somewhat flawed as at the start when you purport to be setting avast to the highest scan settings, you are changing the sensitivity for the on-access Real-Time Scans, file system shield and not for the on-demand scans in the Scan Computer section. or for the ashQuick (right click scan) that you did in your test.
If you want the highest settings you would have to create a custom scan or if you are doing just a select folder scan in the Scan Computer section, as the Quick and Full System scans are pre-defined scans and there isn't much that you can change in there.
Though in theory the ashQuick explorer right click scan is the most sensitive, but you didn't change its settings either (image1), so effectively you wouldn't have been looking for PUPs or the Highest sensitivity at all based on your video as you change the file system shield settings, which has nothing to do with the scan you did.
I also feel it a bit strange to use a early beta build for any testing, as you don't know if there are any underlying issues that might have an impact. Since this test is also over 2 weeks old and avast 5.1.864 has now been released as a regular version release.