Take a look here:
The Law for Photographers / Travel Photography Law / Legal Issues of Taking Photos
Pay particular attention the section labeled "Publicity and Privacy Rights of Individuals"
Also go here and look through the various state level information
Photographers' Guide to Privacy
This section is of particular interest
9 Keys to Avoiding Invasion of Privacy Suits
There are many resources out there to research, but if you have a doubt - get a release. For instance - when you send an image to National Geographic for their "Your shot" submission - they clearly state that a person is recognizable, then you must also have a model release (they have a link to one you can use too). On PPG - they suggest that model releases should be available whenever possible. Even this site has the rule that you should be the owner of any image displayed and that any appropriate releases should be on hand if the case arises. This should be taken very seriously if underage individuals are included.
Also, in the case of the OP's U-Tube movie - particular attention should be noted about the copyright of the music included. With all the hoopla going on with pirated music - T-Tube is most likely pretty sensitive copyrighted music distribution.
As for photography, if you are in a public space and you are shooting people in that public space, you do not need model releases. However, as a general rule - when in doubt get permission in writing. If you shoot someone in a public place and they come after you, then get a good lawyer - and ask for triple damages, because they will lose.
Edit: As a photographer you do have some rights - download this document and enjoy.
Bert P. Krages Attorney at Law Photographer's Rights Page
A photographer was awarded 8K USD for taking pictures of Police activities. The activates were on public property and he was not charged.
Search Results | Seattle Times Newspaper
The last sentence is of particular interest (at least with reference to police activities) "Caplan said the public has a right to observe and document police activity that occurs in a public location." (Caplan is Aaron Caplan of the ACLU)
The Elitist - formerly known as PDL