The media coverage on this is full of inconsistencies so its hard for joe public to have even a half a clue whats going on.
His wife says in her statement he "went for a walk" but this isn't the same as heading back to the accommodation which the media are reporting. A walk implies he was coming back, whereas heading home means just that. The media talks about him looking for a bus back, and for whatever reason this wasn't taken. Also the media says he wasn't feeling well, though where did that info come from?
What we do know from that cctv is he is heading completely the wrong direction to Symi (where he's supposedly staying). He looked confident in the footage, striding with purpose on flat terrain. Why then would he decide to scale a ruddy great mountain. Take a look on google earth or any other photos of the area. He's a clever man, he's wearing trainers and clearly not equipped in midday sun for a jaunt up a gnarly mountain. It doesn't add up he'd be so foolish.
Plus... we didn't see him walk up any treacherous mountain as the media implies. He walked past the marina, nothing more. It's just as unlikely he got offered a boat ride and then went somewhere. It's more likely he kept walking, realised he'd come to the end of the built up area and turned around. It's unfathomable!