I am following the video tutorial on the Vimeo website for rendering from Vegas for Vimeo and for some reason my videos appear to have issues (possibly with interlacing?) as can be seen in the sample below. I am using Vegas Pro 10 and rendering as Sony AVC exactly as described in the tutorial..

Any ideas what might be going on here or can someone recommend better render setting for Vimeo, Youtube, Facebook, etc?

spotlight on Vimeo

I forgot to mention that the issue I am seeing is with the trailing horizontal lines during motion. It's more apparent when viewing in HD.

This is almost always due to having selected no deinterlace method in the Vegas Pro project properties when using interlaced footage which is scaled during render.

If this is the case in your project, set the deinterlace method in project properties to either "Blend Fields" (which is the default) or "Interpolate Fields".

There are only very few cases when selecting "None" makes sense for interlaced footage.

These lines are from interlaced content. You in one of the stages ignored the fact that your video is interlaced.
I replied too late...

Thanks! I'll give it another try tonight. I think you're probably right!

That was the problem! The deinterlace was set to none in the project properties. I'm good to go now! Thanks!

Let me get this straight:

When rendering interlaced footage, if I keep the output video resolution the same as the source, then I should select "None".

When rendering interlaced footage, if the output video will have a lower resolution, say going from 1920 x 1080 to 1280 x 720 (for YouTube or Vimeo), then I need to select either "Blend" or "Interpolate".

Is that correct?

When should I use "Blend" vs. "Interpolate"??

Thanks,

"Blend" makes smoother motion and "Interpolate" gives sharper picture.

There is no need to select "None" as deinterlace method in project properties at all. At least if you use progressive footage it would do no harm. If you use interlace footage it is recommended to always have either "Blend fields" or "Interpolate fields" selected, except you use a third party deinterlace plug-in for deinterlacing.

Just selecting "Blend fields" or "Interpolate fields" in project properties does not deinterlace your video. This settings compared to "None" only determin in which way the fields of your footage will be forwarded for internal video processing. Thus for your editing there is no difference between having selected "Blend fields" or "Interpolate fields".
Deinterlacing will only be done if you select the appropiate setting in the render settings. In this case you can use "Blend fields" or "Interpolate fields" as an selector for smoother or sharper rendering of movement.