Is there a simple program with which I can draw lines in Vegas pro, which can also be followed by motion tracking. Such as Red Giant Universe Uni.Line. But affordable?
I have no idea whether this would meet your needs, but you could draw your line in a graphics program such as Photoshop or AffinityPhoto and export as a png with a transparent background. After importing into Vegas, you could then animate changes using pan/crop plus filters such as deform. You could also pre-render that track using a codec that supports alpha to produce your moving line for use in other projects. Just an idea--probably a bad one--but if it works, it's a lot cheaper than $200 a year.