Hey man, great work! I think the tone is spot on and key points covered.
I think your voice is absolutely fine but if you don't mind would make a couple of suggestions re the script:
1. Re the 51% attack, rather than saying it's difficult to explain (which is true to the layman but might be considered condescending), offer a high level summation of what it prevents i.e 'manipulation of the network' or something similar (someone else on the board can probably provide something suitable!)
2. Suggest dropping the 'we're small now' line at the end, as although it may be true, if this video and the other marketing initiatives have the desired effect, you'd need to be changing it anyway in the near future!
3. Not script related, but on the 3rd or 4th time the word GoldCoin appears, it has a small 'c'.
Will make a further GLD donation when I get home!
Sent on the move