I hold scrum meetings with my developers and tech team every day, so I think a good agile software and a disciplined project manager are probably the best source for scrum and learning about it. There is nothing like a good project manager to act as a scrum master, but one experienced specifically in scrum itself.
I have personally utilized YouTube as a good source for scrum meetings, but do not forget that Agile is also the counterpart to scrum meetings.
If you'd like to speak about this in more depth, I'd be more than happy to work with you and show you what scrum resources have worked for me.
Have led one engineering team and worked with a much larger geographically distributed team, the answer depends on your specific situation.
Many advocates of Agile insist that it can only be done properly if engineers and your internal product experts are the same location, or at least in the same time zone. You mentioned "Scrum" but didn't say this was case.
Unfortunately, "Agile" and "Scrum" are these sexy buzzwords that entrepreneurs and managers like to promise to investors even when they cannot possible practice Scrum because their engineers and internal project managers are on separate continents. They practice some sort of non-Agile methodology, although to keep the investors under the illusion of Agile they'll hold "Scrum" meeting and use Agile buzzwords. They will doing something very specification heavy, or with much slower iterative cycles, but they'll still run around insisting they are doing Agile.
Google and other large corporations apparently have mathematical predictive models for figuring out the number of engineers required on any one project. "Lean methodologies" like six sigma may also try to build these from your existing client data. There is a group at Carnegie Melon that studies (and consults on this) and has found that geographic distribution plays a major role in the optimal type of methodology (Agile versus non-Agile) you should be using on your given project.
So I would need to know a lot more about your project management and engineering organization to answer this question. Are you a small start-up or a large organization? How existing data, if any, do you have on completed projects? Will your software engineers be nearby or on a different continent.
If need help figuring out the ideal methodology for your project, the CMU group I mentioned has published a number of books available off Amazon that can help you make the optimal selection. If you are a new organization starting from scratch but really are doing Agile/scrum (and not just running around saying this to impress investors) there are, of course, very good books and YouTube videos on scrum methodology.
If you're an existing mid-size to large organization, your PMs or in-house six sigma experts might be the best people to ask. Regardless of whether or not you already have a six-sigma (or equivalent) style organization in house, getting access to the past project data that these sorts of experts look at can be extremely valuable. You can figure out the pain-points in each project, and the amount of engineering and time resources that each pain point typically requires to address.
I'd be more than happy to further share my expertise on a Clarity call.
In my experience, the best way to learn about Scrum is to attend a Scrum course by Scrum, Inc, and in particular, taught by Jeff Sutherland. Jeff is the founder of Scrum Inc and has A LOT of experience.
Course listings are here: http://www.scruminc.com/scrum-courses-and-training/course-list/
At Webs, we tried doing scrum without this training, and we ended up doing it all wrong for years. Our velocity was constantly going down, and we kept trying to fix it to no avail. During Scrum training, Jeff goes through WHY all of that happened, and how to implement things the right way. His experience with a broad array of organizations really helps him understand what YOU will need to succeed. (Definitely ask questions about your specific case. He will have answers.)
I'm not big on training courses in general, but this course should be thought of as necessary for anyone implementing scrum.