Hello sir,
The strategy you are following is not upto mark and it makes more load on hosting server.
I have one very better idea, which will definitely work without any lagging or any timeout and in future if you expand the servers than also this will fit so, it will work on very scale level as well.
I am prefer to use the service Amazon Lambda, its event driven stateless processing server. When any event trigger at that time it just start the processing.
So, the full scenario like your hosted server will not keep any our your video file on the server instead it will store the video file on Amazon S3 and S3 will fire the event and lambda server to process the video and save it back to S3.
You customer will just get the video back from S3 server only. This is the best and scaled solution otherwise as per your current architecture if 1000 of video requires to processing at a time than it will just down the other running services on the server.
Now, I can suggest the another one based on your current architecture.
One socket service will be running on server A. Any other server who want to process the data will communicate with that socket service and get the data back from the same one.
Using socket we will overcome the timeout problem but definitely say that it will not give that through smoothness that you got on server A.
Above is the better solution otherwise have lots of others.
Price will be change according to the solution. Its a minimum price.
Thanks,
Chetan