Try running four or more Flash videos at the same time and then compare with the other players. The Adobe Media Player and VLC seems to be less scalable.

Player that let's you open multiple windows in the same time. The Teppefall supports Flash FLV video on all platforms and WMV on Windows. The system also supports third party codecs that are installed into the DirectShow, Quicktime or Gstreamer frameworks.
You can open multiple videos at the same time and even multiple videos within the same software window.

Full screen support is available for the primary or secondary screen. Standard features are mute, volume, restart, seek, timer, repetition and the capability to let the window hover above all other applications. In short, the media player supports the features you need for easy access to common Internet video.
The player also supports external applications that are influenced by metadata sent from media providers. The player can play URLs, local files and files from RSS feeds.

The Teppefall Media Player is now available as a beta for Windows and Mac OS X. Java 1.5 or higher required.

Requirements:
* Java
* JavaFX SDK

The license of this software is Freeware, you can free download and free use this media player software.