Updated FAQ

FAQ.md

@@ -3,6 +3,7 @@
 - [Why use MediaWEB and not any other similar software?](#why-use-mediaweb-and-not-any-other-similar-software)
 - [Is MediaWEB secure?](#is-mediaweb-secure)
 - [How do I view my media?](#how-do-i-view-my-media)
+- [Why are the Video thumbnails not generated?](#why-are-the-video-thumbnails-not-generated)
 
 ## Why use MediaWEB and not any other similar software?
 
@@ -17,7 +18,7 @@ Yes, MediaWEB only allows read access of media files whithin your media folder.
 
 If you protect your content using a username and password (enable in mediaweb.conf) you should enable TLS/HTTPS, otherwise it would be possible to sniff the network for your username and password.
 
-## How to I view my media?
+## How do I view my media?
 
 Unless you have changed the default port in mediaweb.conf (9834) open a web browser and enter following address:
 
@@ -27,4 +28,14 @@ For example, if your IP address is 192.168.1.104 enter:
 
     http://192.168.1.104:9834
 
-If you need to access your images over the Internet you need to enable port forwarding in your router. 
+If you need to access your images over the Internet you need to enable port forwarding in your router. 
+
+## Why are the Video thumbnails not generated?
+
+Secure that you have installed [ffmpeg](https://www.ffmpeg.org/), and that you have ffmpeg in your PATH environment variable. You can test that ffmpeg installed and your PATH environment correctly setup by opening a shell (bash on Linux or cmd.exe on Windows) and enter:
+
+    ffmpeg
+
+If ffmpeg is found it is correct. Secure that you have restarted the mediaweb service (or your computer) after the ffmpeg installation.
+
+If only some videos don't have any thumbnail it is because the video format is not supported by ffmpeg.