Does this also occur on other types of files such as Word documents, Adobe .pdf documents, photos files, windows system files, etc. and not just on movie files? I don't view files in my W10 file explorer as icons, usually list or details view unless I'm looking for photo thumbnails or .pdf scans.
Also it turns out there are 3 different builds available on the Anniversary Updates: [v1607 b14393.0, v1607 b14393.5, v1607 b14393.10]. We need to know which one you have. If you don't have v1607 b14393.10, then you don't have the latest version. You need to re-run your "check for updates" in Windows update again until you get that. Retest for the same problem and post back your result.
To check which version you actually have on your computer, use the windows+logo-key + R-key together, brings up the run command box. Type in the command "winver" into that box and hit the <enter> key. This will produce the EXACT version of W10 you have, and the EXACT build number as reference in my Post above, there are 3 build numbers under the KB3176929 release. You will want to make sure the winver command returns the v1607 b14393.10 build. If you don't have your computer updated to that you could be experiencing spurious problems. We have seen a whole bunch of oddball problems on the first 2 versions of v1607-KB3176929 (b14393.0 & b14393.5). This doesn't sound like much, but with an update this large (it's the size of a Service Pack such as Win7 SP1), you have to be running this latest version.
You may also have to go into your Windows Update settings and set WUDO (Windows Update Delivery Optmization) to enabled, and maximum network delivery using the WUDO=ON, and PCs on my local network, and PCs on the Internet setting. This can be reached through the Advanced Options button in the Windows Update settings page.
Once you are at the v1607 b14393.10 build, retest viewing your video files and other files and see if ok. If they are, your problem is fixed!
If it's still not fixed, then I suggest that you have some other windows corruption, virus/malware infection, or failed hardware component such as 1 or more RAM Sticks or Hard Drive. What is the Make/Model of your computer? Is it a desktop PC or a laptop? Is it a self-built or custom-built PC? Or is it an OEM computer (Dell, Acer, HP, Gateway, ASUS, Toshiba, Samsung, etc.)?
We suggest you use your existing AV program to scan/remove any and all viruses found. Also, download the free Malwarebytes antispyware program from Malwarebytes.org; scan and remove any spyware viruses detected. Restest. If fixed, you had a virus causing this problem and you are set to go.
You'll notice that if you find any failed hardware components, you will have to reinstall your W10 using a clean install made from an ISO file download burned to DVD or USB from the Microsoft website. Use this link and the MCT tool (Media Creation Tool) to make bootable W10 media and reinstall your W10 on your computer: https://www.microsoft.com/en-us/software-download/windows10