How do the whites look on a properly calibrated professional monitor? Your computer screen is not a good way to judge color fidelity.
If you want deinterlaced material, shoot as progressive.
You've told others on this forum to use professional monitors.
Not everyone has access to a professional monitor. I will never have access to a professional monitor. Not everyone is a video professional and not everyone cares to be one. I just want a video that looks good on YouTube. A professional monitor is not an option.
All I know is that on the same monitor, when playing the originals and the final exported file the whites look noticably more blown out than they do when previewed within Premiere.
The D300s only shoots in progressive, but when I export from Premiere (making sure Progressive is selected) the video looks interlaced.
You have to determine first if the originals look good or if its your computer.
View the footage on another computer or hook the camera to a hdtv if possible.
I just want a video that looks good on YouTube.
You can't always get what you want. This is such a case. Because you have no control over how other users' monitors are adjusted, you have no control over how good your video looks to them.
You can only control how the video looks for you, and to do that, you need a properly calibrated TV (not a computer monitor).
Sorry but, that's just the way it is.