The above video is a Burley (the company famous for the bicycle trailers for kids). Another trailer which gets good reviews is the Houndabout by Solvit:
I am leaning towards the Houndabout. Looks more comfortable for the dog; looks a bit like a dog kennel on wheels. The Houndabout comes in different sizes; the blue version is for large dogs up to 110 lbs. There is a red version for dogs up to 50 lbs.
Have talked to a number of people with dog trailers and received good feedback in terms of cycling. I think the challenge is whether the dog itself will like or tolerate the trailer.