AOSP ROMs Video Playback Capability I have one problem with AOSP roms and I consider this as the biggest one.
I have a Galaxy S3 I9300 running Stock 4.3 deodexed, zipaligned etc.

Now with this ROM I am able to play almost all types of video files...Why is this not possible with AOSP roms?

I have always seen people installing different types of Apps (MX Player, VLC Player etc. etc..) to get all the videos playing...
But TouchWiz plays almost all types of videos out of the box...As of now I don't have any third party video player installed on my phone...

I am a big fan of CM, but refrain from installing it just because of this one reason!

Can someone please explain this to me...would be great !!
And please correct me if i am wrong...

Thanks.
AOSP Video Playback
Samsung's Touchwiz framework includes Samsung's own Video Player for Android. It's a decent player and covers a lot of different video formats.
AOSP (Android Open Source Project) ROMs come with the 'Stock' video player, which does not seem to have the wide array of features that Samsung provide.
Samsung Video Player APK:
I found a link to the apk for Samsung Video Player.  Here is the player
As you said, you would have to install VLC, MX or an alternative player on AOSP to enable more video formats. I think the trade off of downloading an app, vs reinstalling the laggy, bloated Touchwiz is an easy choice, but it depends on what you prefer. It'd personal choice really.

Galaxy S5 Video Player
You can actually install Galaxy S5 apps on your S4/Note 2/3 as well.
This XDA thread has the apk files for Galaxy S5 applications, including Video Player

Added Bonus: Other Samusng Apps:
This XDA thread has Samsung apps you can flash via custom recovery. However, it requires a custom recovery, and the Video player is not listed. Here are the apps you can install, perhapst he Samsung App Store would have the Video Player:
Samsung apps store 
Polaris office
Touch Wiz 4 HD Launcher
Touch wiz clock package
Samsung Task Manager
Memo (not S Memo)