That is because it has DLL for the drivers and it is avery big zip file with DLL. This is totally normal :)
If you follow the steps then it will wipe the phone for you :)
It is a latest build with new firmwares. Build date is May 27 2015
As we all know that there are some touchscreen issues with OnePlus One and as promised by @Carl that we will be releasing a fix for...
Your ticket is with our Replacement team :)