That's right. You have to run your program to see if it does what you coded (nobody's perfect). To run certain parts you must even write helping code, little programs that you can leave along with the main source code. Those are tests. You should run every critical verification using an external code that you (or everyone else) can run again to see if it keep working when the code changes.

Imagine that you change a code many times for different reasons. Would you explain every possible change you did? For frequently modified code, nowadays you have an alternative for this kind of comments (and others): Putting them in the Versioning Control System. It will store not only the comment, but who changed the code and why, what other changes were made at the same time, when it was done and even all the rest of the program at that point. And code will remain clean and coming with only general explanations about it.

After including one of them, you should always include a copy of the book or the webpage along with your code, and everything will be OK. Space is cheap, isn't it?

I use the All-In-One Video Bookmarklet under Firefox. In my system I couldn't have the sound from Flash working properly, and last version was not even an option because its poor performance. At least, Youtube is the only site that allows viewing videos using the old version 7 Flash player.