Re: "why the algorithm..such a heavy weighting on..only 2% of the footage."
it's possible that the algorithm weights frames according to its confidence in those frames. So if the tiger frames were muddied by surrounding distractions but the car shots were clear and contrasty, it would have more confidence in those images than the tiger.
This isn't really a bug, it's a complication in the tuning. Especially when given input deliberately intended to deceive. Human recognition is also prone to deception - so called 'optical illusions' - and is far more difficult to correct.