I'm using a Mv4 video file in my video inside a 1920x1080p project. Open the file in the trimmer and selected a portion and drag it onto the timeline.

When it plays back it pixelates during the clip where there's movement. What is the proper way to handle this. Found a mv4 to avi converter but the larger original clip says it'll take 4 hours to convert the clip.

the file downloaded is a M4V FILE 718X489 AND i'm importing into a 1920x1080p project - it pixelates on playback - anyway to make the footage somewhat acceptable when viewed - it's only a 5 sec clip but it's be great if i could make it look better.

I'm rendering out to 1280x720 final video.

Well the aspect ratio of the source video (1920x1080) is 1.778 (I render to same a/r at 1280x720)
the video I have from the source (718x489) is 1.468
so is it possible for me to set the video to 1586x1080 somehow such that it doesn't distort? Pan/Crop in reverse somehow?
I'm using FoxTab AVI Video Converter to convert the mv4 to an avi. I suppose this is the place where I need to try any resizing. I'll report back on what I find. I can tell whether the resultant AVI file though larger looks ok.

Try setting your project properties to 1280 x 720 since that's what you want to render out to.
That way, you're only blowing it up 2.6 X instead of 5.9 X to match the project properties.
An almost 3X blowup is still going to look rough though as you're asking a lot of it.
What I would do is keep the smaller file at it's original resolution and find an interesting background to lay it over top of.
In the past, I've duplicated the layer, placed it on a lower track, blown it up to the desired resolution and applied a gaussian blur to it.
TV Stations are doing this a lot in the 4:3 to 16:9 transition and it can work if done effectively.

So the original clip can still play at it's original size within my larger size project? I'll have to look at the settings. When i drag the section from the trimmer i suppose it's auto reasizing to my project - if i can turn this resizing off and it play in the smaller size that would work maybe against a backdround of a stage since that's the perspective of the video clip - a Braodway play clip.

So the original clip can still play at it's original size within my larger size project?

It sure can.

When i drag the section from the trimmer i suppose it's auto reasizing to my project...

Yes, that's what happens.

if i can turn this resizing off and it play in the smaller size that would work ...

Open Pan/Crop on the smaller clip and set the Width and Height values to that of your project properties.
It should now be shrunk down to its original size so that you can place it over top of whatever you want.

Mike I tried this and it simply did not work. The original did get smaller but would not play without massive pixelation since I think the aspect ratio was different perhaps....

Course I'm playing in review window but selected full size and best for playback....