W has released a new behind-the-scenes clip of the filming of a trailer.
In the clip, Han Hyo Joo and Lee Jong Suk display their friendly nature whilst filming in other locations. First, we see Han Hyo Joo playfully greet Lee Jong Suk and discusses with him as a celebrity.

Then Lee Jong Suk has to hit his fist opposed to the plastic wall which leads to some pain. Han Hyo Joo briefly asks him if hes alright after filming this section.
Han Hyo Joo presentations her quirky charms with a adorable dance as well. Later they wrap up filming and Lee Jong Suk talks about lacking his mom.
Hong Si-wan, Seoul