How can I avoid recording on demand programs?

No there's no way to avoid on demand from being recorded when you do a search, you have to schedule any recordings directly from the guide to avoid that

thanks that is helpful for starters.

Could I also change the series options to record ALL showings, thus it would grab the on-demand, and then later when it was a "normal showing"?

That should work. Try it and let us know. 

On Demand is from each channel's online library. Because of this it allows each network the loophole to disable FF/REW for On Demand as it is not delivered via the satellite feed, so is treated similar to if you were streaming on the channel's website.

Didn't use to be this bad, but over the years more and more networks have been doing this. As this is content specifically with our DirecTV subscription they shouldn't be allowed to do this. Now if it were through separate apps on the Gemini, as that would streaming options not delivered through the DirecTV service itself (so just like an app on a Roku or other device) then that they can mess with if they want.

The search feature needs to be improved so you can sort between satellite and On Demand, as well as make sure it is a channel you are subscribed to. One alternative is setting the recording in the guide so it only pulls from the channel you manually choose.

This issue is not exclusive to the Genie-2 (HS17). This is a complaint with On Demand in general.