Shadow files are small low-resolution copies of the main media files and are used to reduce the computational load on the computer and make editing smoother when the main files are large and hi-resolution.
The icons in the media window go yellow whilst the low-res files are being generated. They are not ready for use during this time. Once the generation has completed they go green and can then be used.
When you produce the finished video the shadow files are replaced with the original hi-res content.
Regards,
Mike
Home-build system:
Intel Core i5 Quad Core 3.3GHz, 2 x 4GB DDR3 1333MHz,
Asus Nvidia GT440 1GB, 2 x Western Digital WD10EARS 1TB, 1 x Seagate ST1000DM010 1TB,
Windows 7 Prof 64-bit, PD 9 Ultra 64, PD 13 Ultimate 64