i have used only the Windows live movie maker with option high definition display (1440 x 1080)
but the size of the file was about 312 Mo , in this raison i have used the AVS converter with the same extension WMV, the file become only 41 Mo, so it easy for me to upload the file into the youtube without losing the HD.
but it depend olso for the render of the pictures, for me i prefer the size 1000x 500 or 600 with quality o.6 or 0.7.
sorry about my English.