Comment by jszymborski

Not an expert, but this is my understanding.

1. It is necessary for nonces to never be re-used for a given key lest you open yourself to a certain class of attacks that can decode all messages using that key. This is specific to AES-GCM due to how it internally reuses nonces.

2. AES-GCM uses very small nonces, making the probability of randomly using the same nonce unacceptably as the number of messages encoded with a given key increases (as it would with each frame sent on 1fps).

You can avoid all this by using a different primitive with a longer nonce such as XSalsa (a version of Salsa with a 192-bit nonce)