Former hockey player Mike was pictured by Hilary's side as she arrived at the set of the promo in Los Angeles on Thursday (4 September).
Hilary and Mike – who are parents to son Luca – have remained amicable since separating in January following three years of marriage. So amicable, in fact, that constant rumours swirl that they could give their romance another go…
The star has hinted that although she and Mike are apart for now, things might change in the future…
In a recent interview, she said a song on her new album was "my love for this person, that maybe we're not meant to be together, maybe we are. It's very, very personal."
Whatever happens in the future, it's clear Hilary and Mike have a lot of love and respect for each other and are dedicated to ensuring son Luca, two, is their priority.
Earlier this year, Hilary said: "We love each other so much and we love spending time together, so when you see us out, it's not just for Luca, it's because we make plans and we hang out."
Yesterday, she was in LA filming the music video for new single 'All About You', which is taken from her upcoming studio album – her first since 2007 record Dignity. It's the follow-up to comeback single 'Chasing The Sun'.
Unfortunately for fans, they'll have to wait a bit longer to hear the album...
Hilary tweeted this week: "Guys hate to break this news but the album won't be out in October... You will have to wait a few more months. Love all the excitement tho."
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Watch Hilary's video for 'Chasing The Sun' below: