Effectively, this can broaden the context the network can learn. There are relationships that are readily apparent to something that learned images that might not be apparent to something trained only on text, or vis-versa.
It will be interesting to see where that goes. Will it be possible to make a singular multi-domain encoder, that can take a wide range of inputs and create an embedding (an "mental model" of the input), and have this one model be usable as the input for a wide variety of tasks? Can something trained on multi-domains learn new concepts faster than a network that is single-domain?