How to Crop avis and how to make Fixed Size on Avis
STEP#1
Select the rectangular Marquee Tool (M)Then select on your document which you want to stay, like this:
STEP#2Then go to Image ---> Crop

Then the black things would be gone.
But if you want a fixed size. Then do it like this:STEP#3Select LAST Layer:
STEP#4Create a group and select all the similar layers, then put them in the group, like this:

(you can close the group if you want.)
STEP#5Click on Convert to Timeline.
STEP#6Then go to Filter ---> Convert for small Filters

You will have to have rectangular Marquee Tool (M) selected.
STEP#7Select the ---> Fixed Size on bottom
STEP#8Then write the size you want to have your document. If you done it, then click on your document, then you will have automatically marked the size you wanted on your document:
STEP#9Then when it looks like this, then just go to Image ---> Crop
Then select NORMAL again and click on the *grey* background to have the marked thing gone.
STEP#10Your document will now have your wanted size. But when you click on play, maybe the video is not in the right place where you wanted, then just select the : Move Tool and move your avi till you like it. (If you didn't want to move your avi, then you don't need to slecet Timeline and Convert to Smart Filter) then save it with : Save for Web & Devices
I hope, this Tutorial helped you a little bit :D
Buhbye! :D