In my test DNN installation, I created the following folders:
\Portals\_default\Skins\Bootstrap
\Portals\_default\Containers\Bootstrap
Then from the zip file
zzze_Bootstrap_Skinning_Part2_7719.zip
I copied the contents of the Skins folder from the "Bootstrap Skin Resources\Complete\Skin\Bootstrap" to the folder \Portals\_default\Skins\Bootstrap. Similarly, I copied "Bootstrap Skin Resources\Complete\Containers\Bootstrap" to the folder \Portals\_default\Containers\Bootstrap.
Everything looked fine and matched the video until I click on Login and then I get the error message:
[HttpException (0x80004005): A potentially dangerous Request.Path value was detected from the client (

.]
System.Web.HttpRequest.ValidateInputIfRequiredByConfig() +12703455
System.Web.PipelineStepManager.ValidateHelper(HttpContext context) +166
I am running:
DNN v7.3.1
.NET 4.0.30319.18444
Microsoft-IIS/7.5
Microsoft Windows NT 6.1.7601 Service Pack 1