When an extended crank hard start exists and there is NO check engine light illuminated on the dash, one of the often neglected ,and forgotten items to service\replace is the fuel filter.
The fuel filter will trap contaminants and over time can slowly become restricted, and in some occasions cause a lack of volume of fuel to injection system, and in turn create an extended crank situation.
This particular VW Beetle TDI , we utilized the Mahle brand fuel filter,as they are OE.
Mahle Fuel Filter for the 06 VW TDI BEETLE http://amzn.to/2h3Gvbr
Important to replace the fuel check valve that is situated on the filter itself. Re using this can cause leaks and over delivery problems.
Fuel Filter Check Valve (OE) http://amzn.to/2hLXig1
As noted in the video ,it is important to really prime the filter for this particular diesel application and all diesels for that matter with diesel fuel. The TDI is very temperamental, and unlike diesel engines of years past, you really can not get away with using anything but diesel fuel to prime the system.