I found the video a bit disconcerting due to her comments. In my opinion, she plays the game on a fringe, that fringe being heavy roleplay. There is nothing wrong with that if you can find a group of like-minded individuals that enjoy the game like you do.
However, from a centrist viewpoint, more combat than once every 4 sessions would be middle ground lending itself to probably some sort of combat every game session in most groups. As a game designer, you have to consider the full audience of the game and not one element that you are most interested in.
There is no evidence currently that supports she does not understand the role of combat in the game but I am reasonably sure based on comments within the video she does not understand extreme combat or powergaming which is on the other end of the spectrum of players that she is most comfortable playing at. Again as a game designer, she needs to address the powergamer needs as well as the heavy roleplayer
While it's important that the designers of DND address the mechanical side of the game and the people that enjoy it (I love me some char op and build planning), if anything I think it's the other way around and the people who play it for primarily mechanical reasons are the fringe. Given the boom that surrounds 5e, it's tilt away from that, and the success of streams like Critical Role and DCA which are decidedly roleplay oriented, I think it's a pretty safe bet. I'm sure she'll be fine for the mechanical side of the game as well, she discusses the combat role of her character and shows an awareness of the mechanical side of the game, ergo what she mentioned about Way of the Open Palm being the optimized monk and the monk's role in combat and such, but either way I wouldn't be worried, the other members of the team have been gaming for decades and are more than capable of addressing our needs in that respect- off the top of my head I recall Mearls being fairly prominent in 4e which was a very tactical edition, Perkins is a legend, and Crawford has always been excellent.
Additional info: Evidently she worked at arenanet on Guild Wars 2 stuff, which is pretty cool, from her linkedin:
Web/UI Designer, Jan 2011-Jan 2012
- Designed new sites and assets for GuildWars.com and GuildWars2.com.
- Designed the UX and UI for features for the Extended Experience team, including the in-game Trading Post and Currency Exchange.
Web/UI Lead, Extended Experience, Feb 2012-Sep 2012
- Oversaw a complete redesign of GuildWars2.com.
- Designed the beta registration and purchasing experiences for GuildWars2.com, with an emphasis on low barrier to entry and utter simplicity. This included the design for a dxdiag collection tool to keep manual input to a minimum and speed players through the beta signup process. This effort contributed to over a million successful beta registrations.
- Designed several features, including the Guild Wars 2 launcher and the mobile authenticator.
- Worked with a small team to design the box art and packaging design for every element of the standard & collector's editions of Guild Wars 2, as well as provide art direction for the Brady strategy guide for Guild Wars 2.
UI Designer, Sep 2012-Sep 2014
- Created the UX and UI of many in-game features, from initial wireframes to final deliverables.
- Improved and upgraded many existing features as the game evolved.
Host, "Points of Interest", June 2014-Sep 2014
- Hosted a regular 30-minute livestream show on Twitch, spearheaded by the Content Marketing team, to spotlight developers in the company and discuss the PvE (player vs environment) and story side of Guild Wars 2.
and also worked in Game development for Amazon Game studios:
- Currently lead the vision, direction, and execution of the user experience & interface for the upcoming PC game Crucible.
- Responsible for delivery of assets varying from high-level documentation to individual assets, including wireframes, interactive prototypes, and illustration.
- Successfully drove an effort to review & re-engineer the UI solution for Crucible to orient around HTML/CSS/JavaScript-based technology.
- Organized user testing with internal & external test groups to gather, triage, and address feedback. Oversaw the development, launch, and management of private forums to engage early members of the test community.
- Collaborate with every member of the Crucible team, user researchers, and several international outsourcing firms, with a eye toward rapid interactive prototyping.
Yup, that'll do it for qualification, especially those last two points- 5e is very playtest driven and it's been mentioned that they're taking a much more iterative approach based off feedback. I can also attest as a huge fan of guild wars, that if her job involves the creative vision for what the layout of various books and the like are going to be like, then we're gonna get some great looking books- if she was brought on to work on setting guides as some people have been speculating, this is going to be amazing and result in some very nice products. Also if she has any influence over the user experience side of the rules, ditto, because all the stuff she worked on that I've taken part in is great, and user friendly.