If someone sends me a large video file on WhatsApp I believe it is compressed and encrypted. I believe it can only be decrypted on my device with a key that never leaves my device.
If I was to forward this file to another person I would expect it to be encrypted again and re-uploaded from my device. However, the forwarding seems to happen very fast almost instantly as if being forwarded straight from the server.
Any idea how the forwarded party can see the video when it was forwarded straight from the server? Or is it actually uploading from my phone and I am underestimating the speed?