According to JCBrown tutorial 17 (Basic Editing 2) using alt+shift+drag on a trimmed clip on the timeline is suppose to slip the visible content. When I do this, both in Video deluxe 2026 and Video Pro X17, all I get is a black screen. Nothing changes. This happens whether the trimmed clip is by itself on the track or if there are other clips on either side of the clip.

What am I doing wrong? Any help would be appreciated.

Thanks, Barry