Is the form for trials or paid customers? Seems the form is for trials which effects only the # of trials which was only marginally higher. What is the process to convert from trials to paid and is the video really the cause in the massive jump?
There were also other small subtle changes like the addition of "Request Instant Price Quote" headline etc.
I was referring to the accuracy of the test results on abtests.com in general not the site in the link. Many of the A/B examples had multiple changes to the site but only noted one as making a difference.
In your case adding a headline to the form was overlooked.
You were using form submissions as a metric from what I can tell. So changes specifically to the signup form itself (such as the header) is likely to have as much of an impact as the video.
Did you track how many people watched the video then signed up as a metric? That may be more telling.
There were also other small subtle changes like the addition of "Request Instant Price Quote" headline etc.