Question: Is there a way or a program that marks the icon of a file with a badge, similar to how Dropbox marks synced files with a green checkmark, and files that are currently syncing blue?

I'd use that to mark videos I've watched in a series.

Answer: 
I couldn't find a better solution, so I've created an open-source project for that. Available at <https://github.com/csomakk/IWatchSeriez>
Its nothing special yet, but it does the trick, and I'll try to work more on it. I Watch Seriez, IWatchSeriez :)

![enter image description here](https://i.stack.imgur.com/CmmqI.png)
I was searching for a similar solution when I found this thread. I figured out a fairly simple way to achieve what you're looking to do (at least in this particular case.) Maybe it will help others that happen upon this.

If you have the appropriate permissions, you can view "Hidden" files in Windows. They show up as grayed/semi-transparent icons/thumbnails of the original. 

First, be sure that you're able to see Hidden Files. 

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1. Open Folder Options by clicking the Start button , clicking Control Panel, clicking Appearance and Personalization, and then clicking Folder Options.
2. Click the View tab.
3. Under Advanced settings, click Show hidden files and folders, and then click OK.

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Now all you need to do is right click each episode after viewing it, go to Properties, and check the "Hidden" box. It will remain there but grayed out, allowing you to keep your place! 

Cheers!