The folk at Udemy have put together good collection of youtube videos focusing on public speaking. The videos are short, and give good examples and advice on become a better speaker.
Udemy also has a several online public speaking courses for sale. But like many learning sites you may have to look around to find the one that best suits you (hint: click on the courses and check out the table of contents).
They gave me a enrollment of one of the courses, and I got video, downloadable PDF supplementary material and external links.
Personally I think that nothing can compare to getting up and giving a speech in a safe environment (such as at a Toastmasters meeting), but if you are looking for some fast-track information or want to supplement your training, there is some good stuff to be found.
On a side note I have used Udemy for technical training as well, and they have lots of very good courses on a variety of topics. They are worth checking out.