
I hope you are not a scientist, because you're understanding of rationality and evidence is rather poor. You don't take a small sample size of evidence and because it doesn't look like you want it to in the middle of the experiment, deem that it has failed. You can still be hopeful of the outcome despite what the small sample size might say.
What
is rational is to say that while this product might look good or bad from the trailer, it is not enough to say it will be bad. What is rational is saying that I hope the movie will be good despite only seening 2 minutes of it. What is rational is to say, despite the fact that the trailer might not be good, I'll reserve my judgement for the movie itself. Or just not watch it altogether.
I have no idea if it will be good or bad. The trailer was ok, in my opinion, but I'm going to remain hopeful that it will turn out decent. Not just automatically assume it will be bad based on the short sample size.