Haven't tried with anything but my iPhone so far (no wifi currently), but it's worked perfectly so far. I don't know diddly about dressage, so I prefer eventing dressage as it's not so technical and far easier for me (H/J rider) to see the quality of each movement.
Watching on my MAC for well over an hour and it was smooth and perfect - my husband was watching it right next to me on his brand spanking new Toshiba he got yesterday and it froze up and got behind. I don't understand how that works. He's watching archery now with no problems. Does it have more to do with your cable and computer than the signal itself? We were on at the exact same time!
Mine froze during Mary King and came back just in time for Tiana... wasn't wow'd. Wish I had gotten to see a few rides before her to know the test, but I do know it looked like a rotten crooked halt. Oh well. They took a gamble, and it's not paying off. But if Arthur had been the gamble... we might be happy today and disappointed Monday.
Proud Momma of *Capital Kiss* and Bottle Rocket!