BHOA YouTube screen is black, audio is fine

BHOA YouTube screen is black, audio is fine
Just had a webinar, and afterward got this feedback from someone who tried to participate. Has anyone else experienced this, if so, what do you tell them?

The speaker was good, the technical issues were too many. 

First, from my macbook, I couldn't see anything. My screen was totally black. I could not see chat buttons or anything. However, the audio was great - loud and clear.  I logged off and used my iPad mini instead, where I got on, but the screen was very, very, tiny. I tried full screen and non-full screen, both were tiny. Also, I tried to use the chat to ask a question, it brought me to the box, but I was unable to type into it. Furthermore, at one point I got kicked off and then had to rejoin. Constant interruptions didn't help me learn as much as I wanted from this webinar. 

I do a lot of webinars with Yelp! and for my work (acupuncture and health related companies) and rarely have issues like these. I've used a bunch of webinar platforms like GoToMeeting, GotoWebinar, Teamviewer, Glance, etc... but never used Business Hangouts before.  Perhaps the problem is with Business Hangouts or with my Comcast connection today. Also, my iPad mini is totally up-to-date with the latest IOS8 software, so don't think that was the problem. My $$ is on Business Hangouts or Comcast.