The dull answer that doesn't sell papers
Specks of debris from the spacecraft. Do you know how many pieces of debris such as particles
from the control jets and even bits of the LM's gold coating came off during those missions?
A barely visible speck flying by in space does not an alien vessel make. Science expects a
little bit more in the evidence department.
But just as no one is every going to catch the Loch Ness Monster or Bigfoot, no one will
ever do more than replay such videos over and over because digging too deep will take
away the perceived mystery and wonder - to say nothing of the money-making industries
built up around these modern myths and legends.