Video Renderer
The Video Renderer is the component used to display video on your Monitor/TV. Each Video Renderer component has its benefits and its limitations (which you can read about here). In general, the "Overlay Mixer" is the most compatible but can have inferior image quality and is limited to one video playing at a time and only on the primary monitor (it will display a black screen when playing on a secondary monitor or when another video is already playing). VMR9 has better image quality but it requires DirectX-9 installed (a microsoft component) and display hardware (Graphic Card) capable of supporting certain DirectX-9 specific capabilities.

If you're having video issues, try switching the video renderer to "VMR9 Windowless". Under certain conditions, VMR9 may make some video content appear "washed out" (black will look gray, image may look as if the contrast isn't set properly). This is caused by Display Driver issues. Updating the drivers may help, and if not, there are work-around detailed in the Inmatrix Forum.

Custom Renderer
Setting a custom video renderer allows you to re-route video output to a user-defined filter (component). This is mainly used for hardware-specific cases where you have a special renderer that can route the video data to be displayed through special hardware.

Overlay covers entire video area
When using a "Standard Overlay" or "Overlay Mixer" video rendering technologies, Zoom Player can use the overlay hardware to cover the entire video area or only the video area where actual video is displaying. You should probably leave this setting unchecked unless you're experiencing weird overlay video-position issues

Fix VMR9 Scaling Bug (fixes VMR9 issues, but depending on the video driver cause other issues)
When using the VMR9 based renderers, video content containing non-square pixel aspect ratio (some MPEG1/2 and WMV content mostly) may cause image degradation due to bugs in the display card drivers. These bugs have mostly been fixed in Windows XP SP2 and recent display drivers, so in most cases this setting should remain disabled.

Flip Video Horizontally (only works when Video Renderer is set to VMR9)
When using a VMR9 based video renderer, enabling this setting flips the image horizontally.

Flip Video Vertically (only works when Video Renderer is set to VMR9)
When using a VMR9 based video renderer, enabling this setting flips the image vertically.

Disable Overlay on VMR7 Video Renderer
VMR7 can work with overlay hardware or not. Depending on the video hardware, using overlay will incur image quality loss and on other video hardware image quality may improve. So if you want to use VMR7 technology to display your video, try it with overlay on and off.

Enable YUV mixing on all VMR modes (less CPU overhead under some configurations)
YUV mixing with VMR video rendering can reduce CPU load on some systems, but depending on the compliance of the graphic hardware drivers, it may break media playback entirely.

Prevent VMR Video Renderers from correcting Aspect Ratio (can fix image-resizing artifacts)
The image artifacts described under "Fix VMR9 Scaling Bug" can usually be fixed with this setting enabled, without any stability issues. This setting should remain enabled unless you're experiencing weird issues related to Video Rendering.

Use Exclusive Fullscreen with VMR9 Renderless mode (use with care)
When the video renderer is set to VMR9 Renderless, enabling this checkbox enables "Exclusive Fullscreen" mode. This means that when Zoom Player goes fullscreen, it prevents background applications from accessing the monitor. This can improve image smoothness with bad drivers, but at the cost of eliminating access to background application and even to Zoom Player's own navigation interfaces. Use with care.