When talking about BSD license, you have to be aware that there is not one, but actually four different BSD licenses. The most basic is the zero-clause BSD license which is a public domain license which doesn't even require attribution:
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
The LGPL and GPL + the Classpath exception share the property that if you link code under these terms into your program, the resulting derivative work does not have to be made available as free software. Instead you can copy and distribute the resulting binary executable under terms of your choice. This means that the source code does not have to be ...
My understanding is that if I embed a CC BY SA work in something, say a [...] song in the background of a video, the work does not have to be CC BY SA
I think this may be a misunderstanding. Looking at CC-BY-SA 4.0, it says in s1a
For purposes of this Public License, where the Licensed Material is a musical work, performance, or sound recording, Adapted ...
Do I have to release my code if I make some changes to it? [...]
Yes for the GPL, as explained below. But only if you redistributed the code and not as a general public release.
[...] and do I have to let the author know about it?
No, but that's a nice thing to do.
Also is there any difference between commercial use and personal use?
No. There is a ...
Kyle E. Mitchell on /dev/lawer makes a compelling argument against using no-attribution licenses like 0BSD, et al.:
Some recent licenses, like 0BSD, omit attribution conditions. There is literally nothing users have to do to use or reuse work under these licenses. That’s the ideal of “anti-licenses” like WTFPL and also public domain dedications: Anyone ...
Copyright James Daniel Marrs Ritchey. This material was created for
'Recommended license for small script without an attribution clause?',
but can also be alternatively obtained from
under the terms of any of the following licenses: Ritchey Permissive