Animating appearing/extending strip with gaps As i am new to blender i decided to learn by recreating some animations which have some interesting problems, and gain more knowledge about how tv intros are being done, collecting some parody intros to videos. I came across a simple yet troublesome effect , found no answer by googling or getting through tutorials and testing methods on this case led me to nowhere. 

https://youtu.be/amyFUdwQc6Y

I attempted to recreate the animation above, especially  the extending/appearing/drawn white strip with "randomly" placed gaps , strip which travels just above surface , casting shadow. 

Tried dynamic paint,( with alpha channel) image sequence texture but although effect was very similar, whole invisible strip was casting shadow being Z transparent, in places where white color haven't reached yet.

I tried bezier curves as well(vector mode) but it appears that taper cant profile part in squary way, or maybe i am missing something here.

Shape keys seem to hard way to go , while keeping whole animation of stripe "unrolling" at constant speed.

I tried as well putting an array of planes on the path but it is completely not what i attempt to achieved. 

I will edit post and add some pictures tomorrow.
There are a few methods that you could use to achieve this, some simpler, some more flexible. The one that follows can give you results similar to what's shown in the video.

First create a curve object that roughly follows your desired path, bevel its corners so you get less distortion on tight curves. In this example I use the great Curve Fillet Tool addon from the Blender CG Cookie Market (it's a paid extension, but worth the price IMHO), you can also use the Simple Curves Addon or just do it manually if you prefer.



Now add a plane object, scale it lengthwise so it's narrowest side is placed along the curve length for better precision. Also scale the other direction to match the desired line thickness. Make sure you apply the scale before proceeding.

Add an Array modifier to you plane, and set it to Fit Curve and pick the previously created curve. Tick the Option Merge to join the arrayed planes.

Now add a Curve Modifier on top of it, set it to the same curve and it should distort it along the curve length. Make both the plane and the curve coincide at the same scene coordinate to avoid unwanted distortions.



Now the magic all comes from a Build Modifier, which will make the strip like effect progressively grow along the curve as desired. (Scrub the timeline to see the effect)



If you want more control, optionally apply the Array and Curve Modifier Modifiers only (leaving the Build Modifier live) if you later wish to manually adjust the shape of the strip, like different materials along the path, varying width, colors or add gaps, otherwise leave all modifiers live for a more flexible non destructive workflow.