[Filmania]

"when a body has died if clinging has no ceased then "I am" shall continue to arise"

As I understand means at the death of one ego-identification in the mind, if there is still tendency for clinging in the mind then there will be many future mental births as "I am".

kammas effect can be felt accross lives

A life here is the duration of one mental birth and death. So whatever action you do based on this mental "life span" will effect the next.

For example, you kill someone out of anger. When you killed the person you felt no regret or remorse but contentment. Once the deed is done and the police starts the investigations you start to feel scared that you will be caught. You sit down and regret killing the person. First you were born mentally as an "angry killer" and the actions done during that birth triggered, at the event of death of the angry killer, another mental birth as a "scared/guilty man". That seems to be what BB is referring to when he says "kammas effect can be felt accross lives".

I don't think it has anything to do with physical birth or rebirth