I'd heard rumors about this, so I've watched for it. I was a physical therapist for 20 years and have worked rehab and acute care.
If this IS true, it's extremely minor. Clinton has an ad out here in Hawaii where he's obviously reading from a script, so that ability is intact, as is his speech. He doesn't come off as charismatic as usual (hey, I can't stand the guy but he does have a detectable charm) but that could just be fatigue. I watched video of him and there's no sign of any paresis anywhere. The face often will betray a very mild stroke. Couldn't see it.
Things that wouldn't show up in the video would be more subtle - impulsivity (hard to detect since he's always impulsive) and memory. Perceptual ability is less likely since that usually shows up in gait as well.
Your detector is much more sensitive than mine. }8^D