It all depends on what type of AC(aircraft) is flying the route. From taking a quick look at the timetable at CO.com it appears that 4 different ACs (737-300/500/700/800) fly BOS-IAH-BOS route.

If you are flying the 737-500(735) there is NO audio or video entertainment provided by CO. However, you will recieve a meal at meal times which having not flown coach in while I have no idea what it is now.

If you are flying on the 737-300(733) series you may or may not have audio/video entertainment, only a few of the 733s had audio and video equipment installed. However, once again you will recieve a meal at meal time.

Lastly if you are flying on either the 737-700(73G) or the 737-800(738) you will have have both audio and video entertainment available. Usually the video portion is a movie followed by some short subject programming. This months movies can be found at continental.com as well as the selection of audio entertainment for this month and I believe next month as well. Again, you will recieve a meal at meal times, maybe others can comment on the types of food served in coach on that lenght of flight.

Hope that helps,
Dan