Hi Wraith
What you will need to do is place all the video clips onto one track and then render/export them to one complete track. Make sure you select a high quality level to export to. If the clips are already set up in a track, just click on the solo button in the track name and select export. Once the track is set to solo only this track will export.
Once you have exported the track then the clips are all one large segment and easy to resize.
I hope this make sense and helps you. Please do not hesitate to contact me with any question.
best regards
Cormac