If you are driving and I assume you will be, then do yourself a favour and when you leave Innsbruck to go to Salzburg, stop off at the Ziller valley entrance and take the drive up the mountain to Pertisau. There is a beautiful lake up there and stunning views of the mountains all around it. You can even jump on a large boat and take a tour around the lake. The views driving back down to the Inn Valley are stunning too.
When you get to the valley bottom again, drive straight across to the valley you see opposite and take a drive up the Ziller Valley to Mayrhofen about 30kms, which is the village I lived in for years. Also, take the drive up the Hohen Strasses and again ask where that is, it's a small toll charge but immensely worth it. In fact, there are so many stunning valleys to drive up from Mayrhofen, you could spend two days there easily. Also take the cable car ride to the top of the Ahorn mountain from Mayrhofen and walk to the back valley just minutes and you will see stunning views to photograph. Take a look at my video on Vimeo, the first scenes are from the Ziller Valley and the Ahorn. Search for the video "Austria, Wales, Ohio" and have a watch.
Another great drive is up the Ginzling valley from Mayrhofen, you will get some amazing places to film. I could tell you of loads of places because I lived in Salzburg for years too. Out that way in fact, do visit Hallstatt. Ohhh, and when in Mayrhofen have lunch or dinner at a beautiful 230+ year old restaurant at the end of the village called.. "Zum Griener". It has great food as well as a beautiful place to be in. Ask where it is because it is not readily visible so is one of those great out of the way places. If you would like a contact name and number when in Mayrhofen, send me a PM and I'll give you the contact of another long time friend who lives there and he can point you to all the places I just mentioned and sooo many more.
In Zell am Ziller, which is about ten minutes drive time from Mayrhofen back down the valley, take the time to stop to ride their summer rodel bahn, that too is well worth it and a fun thing to film if you have a GoPro. In fact if you take that cable car by the rodel bahn, up the mountain, that too will give you superb views of the region and some great filming opportunities. I still have not heard back from my friend, I'm hoping he is not on holiday, but at least take a look here for some official information for Austrian flying:
dronespace.at die Austro Control Drohnenplattform - Dronespace
Wish I was going with you, I really miss living in that country, it is soooo stunning.