Consider creating your growth and glow effects in post. This will simply things for you immensely if you can get away with it.
For example, you could create a separate texture for your moving spots by shooting white particles over a black background. Then use the resulting particle flow as a texture map on your phone chord.
You'll want to render a finished phone chord as well as the matte texture on it which you use as a reveal for the finished chord.
That's a less painful way to do it. If you clients need to see specific glowing particles zipping along and building the cable, you'll have to think of something else. =)