I was wondering if there's a plugin that can Flip the Video, I saw the Mirror Effect however that only flips half the video not the whole video, is there any plugin that can flip the whole video?
BorisFX's "BCC Fast Flipper" FX can easily do that and is what I have used when rarely needed. The FX is part of the BCC Perspective Unit - unfortunately it is not inexpensive.
But can also easily be done in DaVinci Resolve (very possibly in the free version) as per https://teckers.io/how-to-flip-an-image-in-davinci-resolve/ - but you'll then need to render the video/s out of Resolve and then import the render/s into Vegas Pro.
Or just right-click the Pan/Crop window and choose "Flip Horizontal" or "Flip Vertical".