Is it possible to change the opacity on multiple clips at the same time?
Not at the same time, no.
What you can do is change it on one clip, select the clip and Copy, highlight all the other clips and Paste Attributes, then select Opacity.
That does the job! Awesome! :D
Really appreciate the tip!
@iamdannywyatt You will notice I moved your question to the Community Support thread from Feature Request. I can't think of a way to do this at the moment, and if you would like to see it added as a Feature, feel free to post a Request using this sticky for guidelines:
Will do. Thanks :)