Read the sentence to find out whether there is any error in it. The error, if any, will be in one part of the sentence. If the given sentence is correct as it is, the answer is ?No error?. Ignore the errors of punctuation, if any. Sometimes, when you are used to/ see a player in the commentary/ box over a long period, you tend to/ forget what a great player he was

The error lies in the second part of the sentence. The form V + -ing is called a gerund if it serves as a noun. In the given sentence "to" has been used as a preposition (in a prepositional phrase) and not an infinitive, thus, the gerund form "seeing" is correct. E.G. I look forward to meeting my relatives. Thus, option 2 is correct. Here, 'used to' is used in the present tense to indicate that one has a habit of doing something.