Compare:
- I saw him run along the street. (Infinitive Complex Object) – He was seen run along the street. (Infinitive Complex Subject)
- I saw him running along the street. (Participle Complex Object) – He was seen running along the street. (Participle Complex Subject)
Such complexes occur after verbs denoting physical perceptions – 'to see', 'to hear', 'to feel', 'to watch', 'to find', 'to catch'.