Hey Wandra!
In terms of saftety and security I would always go with the ship tour...they are probably using a high-end local outfit such as Clark Tours and I would certainly feel 100% comfortable with them.
From what a saw with "Don Gus" he looks like a knowledgable guide, but somethings would make me ask a few questions e.g. where are the lifesavers on the boat? I saw a shot where they were behind the chairs (but couldn't tell if that was Gus' boat or not) and why weren't the people and the Guide wearing them? I actually knew someone who died in a drowing accident on a ferry from Rio Dulce to Livingston...it only looks safe until there is an emergency!. I'd just make sure they are readily available. Rio Dulce is VERY deep and unless people are proficient swimmers I would certainly wear the life saver, even if I looked dorky.
Otherwise it looks like a nice tour if you want to try him. The hokiest parts of the two videos was the region inappropriate music, what's wrong with good ol' marimba (or real Garifuna music, for that matter?).
Realize that unless you are in a town where they are actually celebrating a holiday or local patron saint feast (e.g. Christmas, New Years, Easter, Fat Tuesday, the yearly Fair etc. etc.) any "displays" of traditional dancing, etc. will be staged and put on as show to the visitors. I think the last video had a lot of "staged" stuff because the tour actually coincided with President Berger's visit...they got lucky. My guess is that unless they pay for a "cultural" hour of some sort or if my above mentioned holidays are in play, you won't be seeing this as part of the tour.
The food looked awesome! I read the Posada Delfin's menu and they actually had some of the local dishes, mainly tapado which is a fish stew made with local fish, cocounut milk and plantains. But as with any travel, I would not eat from any street vendors. The hotels look decent enough but I would err on the side of caution with fresh vegetables and fruit if you are nervous. Rather eat it fully cooked or packaged.
I think in Margo's case, if I recall the discussion at the time I was suspect about the sandwich from the boxed lunch they were given...if it sat in a hot car, that would do it. Bananas/oranges always better as your fresh fruit since you can easily peel them and dump the peel...apples pears and grapes...not so.
Hope this helps but let me know if you have any more questions :D