The following are found as to the verb 'see' in Oxford Learner's Dictionaries:
- [transitive, intransitive] (not used in the progressive tenses) to become aware of somebody/something by using your eyes
- [transitive] (not usually used in the progressive tenses) to watch a game, television programme, performance, etc.
But, I came across 'seeing' meaning the above in the following sentences from New York Times. I wondered how the seeing's are justified grammatically.
- In March 2019, scientists studying whales near Southwestern Australia stumbled upon a supersize spectacle that few had seen before — a pod of orcas viciously attacking a blue whale. “Upon approach, we were astounded at what we were seeing,” said Rebecca Wellard, the founder and lead researcher at Project ORCA, who was among the researchers who witnessed the 2019 attack. “When you come across a unique event like this, I think it takes a while to process just what you are seeing.”