We're having the same problems in our FamilySearch center. One of our workers called SLC FS support and they said it was the FSC unit doing too many FS downloads but that it resets after 24 hours. I don't think this is the case. He came in on Saturday and it was fine. Then Tuesday morning, exceeded again. The family history center was not even used on Monday, except by the missionaries who used google docs and things, not downloading copies quantities of documents from FamilySearch. But all this to say, there is no way we've exceeding our download bandwidth *on familysearch* within the last 24 hours.
Maybe you all can corroborate, is it happening when trying to download images from a *film* looked up in the catalog? That seems to be the case with our patrons here. Images are not a problem, if you can find it under the images category. Also, downloading an image from a hint seems to work just fine as well. Even after "exceeding download bandwidth". There's definitely something amiss and it's not what they say it is.