The shows were very interesting and semi believable because they didn't include the "aliens" guy with bad hair.
The things that kept my interest was that the "tic tac" didn't have wings for any kind of lift nor did whatever propelled it show any signs of heat. It apparently also went under water and traveled at speeds far faster than any known submersible.
They had numerous fighter pilots and aircraft engineers that were baffled by what they were seeing and had no answers for it, which also lends to some sort of credibility. The show was worth a watch.