I am looking at a still shot (not sure if there is a video) but this does not look like thrombus to me. It looks like a dissection caused either by a wire or a fogarty. I have had large thrombus burden in the proximal artery in the past and have performed thrombectomy of the artery without a problem

Agreed - on the still shot looks like it could be dissection or disruption. In the past I have had thrombus in the brachial artery proximal to the arterial anastomosis- and I was able to remove it with a fogarty. In another case in the hospital I was worried about embolizing so I had another upstream sheath and used a balloon in the brachial artery distal to the arterial anastomosis and used an over the wire fogarty to pull thrombus from the proximal brachial artery back into the access. Both cases did well.

Was this a thrombectomy case?

IVUS or even 2-D Ultrasound can be really helpful in better evaluating these types of questionable lesions. Sometime we really cannot appreciate what we're looking at with fluoroscopy.

If the flow is strong and there are no symptoms, I'd be less concerned about it.

If it really is thrombus, PTA/ Fogarty may take care of it. Otherwise I would treat a dissection with a prolonged small caliber balloon PTA.

Agree with not appearing like thrombus but more like vessel dissection. Was this an incidental finding or after instrumentation to put pic in context?
Ultrasound can help as well differentiate

But when dealing with pulling thrombus from this site have also experienced effective and safe results using an over the wire Fogarty. The thrombus tends to take the path of least resistance into the lower pressure venous system.

Movie file now attached in original post.

This was angiogram due to difficulty in cannulation
Flow was brisk on Angiogram although there is inflow restriction
Patient had a thrombectomy 4 months ago in this newly placed graft
There was no outflow obstruction

dissection - probably from inappropriate manipulation/instumentation of the artery during previous thrombectomy procedures

This is almost certainly a dissection, I think any attempt at thrombectomy would be not be wise and could very well lead to further injury and thrombosis. It does not appear flow limiting and probably could be left alone.
standard duplex can give you a gray scale image of the lesion which will help clarify what it is and velocities can help determine if it is flow limiting. volumetric flows may help as well.