For an entire series? Yes. Even though the iPad really isn't HD right now, it's a good bet that future iPads will be. Best to pay a little more and get the best available quality now.
For an entire series? Yes. Even though the iPad really isn't HD right now, it's a good bet that future iPads will be. Best to pay a little more and get the best available quality now.
I'm not sure where you're getting those figures from, the iPad screen is 1024x768. This means the largest 16:9 picture that it can display is 1024x576 pixels large. That isn't HD by any definition that I've heard.
To the OP, the choice between HD and SD doesn't have a clear answer. If you are only going to watch the videos on an iPad then HD is only going to give you a small amount of extra detail. However if you intend to also watch the videos on a computer or TV screen then buying the HD version maybe worth it.