Todd Tucker of Eyes on Trade live blogged it. See his post for some basic details, or watch the video here. I'll just mention a couple points (a rough transcription, not verbatim) that struck me as interesting.
First, Senator Grassley expressed concerns about the possibility of incorporating labor provisions into the model BIT. He worried that this was a "poison pill" designed to derail future BITs. In response, USTR Kirk said that the BIT review was not yet done, but he would share the direction BIT policy would take after the review was completed. (At around 85:30 of the video)
Second, Senator Lincoln raised the issue of inspections of foreign catfish, based on health concerns, and which agency should address it. Kirk explained that the inspection process we undertake must be based on science, because if it is not, we could face retaliation by foreign governments, who might do the same thing to our exports. (At around 104:10 of the video)
Third, Senator Roberts suggested that environment/labor concerns should be addressed through other mechanisms (such as the ILO), not through trade agreements. (At around 120:30 of the video).
Fourth, in response to a question from Senator Cantwell, Kirk suggested that the final WTO Airbus decision should be issued (I assume to the parties, rather than circulated to the Members) within the "next several weeks."