I may be wrong, but I don't think that's correct. I think you must observe the act and have probable cause that the act was a felony in order to pursue someone. Here is the judge's instruction -- note the word "observer".
"A private citizen's warrantless arrest must occur immediately after the perpetration of the offense, or in the case of felonies, during escape. If the observer fails to make the arrest immediately after the commission of the offense or during escape in the case of felonies, his power to do so is extinguished."
JMO.
This is why I'm pretty certain the jury will throw up their hands over trying to understand this CA law. I'm as certain as I can be that what I said was accurate, but I definitely get why & how it's very confusing. (Fyi. My understanding is based on all the original dissection of it a year ago, here & elsewhere, and the related GA appellate decisions I read back then, plus listening to every minute of the discussion of CA wording in the charge conference & the follow up discussion before trial began again on Monday).
The original law was poorly written, and as LD said during the charging conference, wasn't intended originally to apply to situations like this.
I really do understand why you think "observer" in the first clause applies to the 2nd clause, but imo that's just not the case.