Can I play Video/Movies content across Multiple appleTV’s in my house with aTVflash?
Not clear what you re asking for?
If you want all the ATVs to play identical content at the same time controlled from one point then this is not a provided facility. However if you are asking if multiple ATV’s can pay media from the same share simultaneously, each ATV being individually controlled then the answer is yes.
Thanks, I am looking to play identical content simultaneously from one point similar to the way I can play music to the multiple aTV’s in iTunes. I was hoping the ATV Flash had a way to to do it. Thanks for your response it gave me another idea.
What you can do on the other hand, is play music from your PC or mac to several aTVs simultaneously.
This is done with Airplay and a third-party-app. For instance Airfoil for Mac. 
You can actually do this without the need for ANY other software. Just start iTunes on any Mac or Windows PC, and select your audio, playlist, or streaming internet radio. When playing, click the AIRPLAY icon in the lower right margin of the scree, and select “Multiple Speakers,” and then you place checkmarks by all the different AppleTV AND other AirPlay devices you have in your home. You can also adjust the volume sent to each AirPlay device with sliders in this dialog.
I just use iTunes to do this, and play synchronized music through 5 different speakers throughout my home and patio.
If you want to control the music and even browse the computer’s library while roaming around, use Apple’s free iOS “REMOTE” app that’s been around forever, and you can even select airplay devices and volume levels right within the app. No extras needed when you have any machine running iTunes.