Google ranking is a weird thing. I did SEO a few years back ’til they changed the rules and took a hit that I kinda gave up after (they knew all my tricks lol oh well – they were common)…
There’s likely different ranking strategies in play for Youtube and Google’s searches – and G+ searches probably even something different.
You’ve got things like: the tags/keywords on your video and their popularity or uniqueness… there’s the title, the description… then it’s likely they have some algorithm that compiles your relative social popularity (which explains your higher ranking on G+ which cares about that, vs Youtube which probably has its own algorithms for determining “first place / second place”).
Sometimes I think that Youtube’s are sorta random – I have a lot of trouble finding some people’s channels… they have the WEIRDEST native sort.
[so I use their advanced search all the time – that works really well].
Anyway – this guy http://www.vpdm.ca/youtube-search-algorithm/ says he interviewed someone at youtube who said their search is a million lines of code
A million lines.
So yeah… ranking is tricky… even on something like your name.